Using oil will yield a crispier crust, while using butter will yield a softer crust. To break up the pecans, I like to either use a food processor or place the nuts in a bag and then smash the bag with a rolling pin or side of a can until nuts are finely chopped. Preheat oven to 350 F. Grease a mini muffin tin. For easier removal, you can put a thin strip of parchment paper inside each tin if desired (see photo). Whisk together the first six ingredients (and 2 tsp spread or oil, if using for a richer flavor). Refrigerate at least fifteen minutes to thicken. Meanwhile, combine crust ingredients in a new bowl, completely breaking up the butter until fine crumbles form. Press 1 1/2 tbsp dough into the bottom of each mini muffin tin, using a spoon or your fingers to make a shallow well in each center. Add about 1/2 tbsp of the refrigerated filling to each well. Bake on the center rack, 12 minutes. Let cool before removing from the tins.: The moment you begin, note how the choice of fat changes the final textural profile, oil creating a leaner, crisper shell while vegan butter yields a tender, almost shortbread like crumb. As the dough bakes you will see the edges take on a light golden hue if using oil, and remain paler and more tender with butter. Listen for a slight crisping sound when removing from the tin with the crisper version. A common mistake is substituting liquids incorrectly which can make the dough too greasy, so keep measurements exact.
To break up the pecans, I like to either use a food processor or place the nuts in a bag and then smash the bag with a rolling pin or side of a can until nuts are finely chopped: Chopping directionally affects the texture and release of oil; the aroma intensifies as you pulse or crush the nuts, and you will notice small particles and a few larger bits, which is ideal for body in the filling. If you use a food processor pulse gently to avoid turning nuts into a paste, watching for a sandy texture. The smell of toasted pecans will become more pronounced as the oils release. Over processing is the most common error here, which leads to a greasy, paste like filling rather than a pleasantly textured one.
Preheat oven to 350 F: A properly preheated oven ensures even bake and consistent setting of the filling, producing a glossy top and edged crust without under baking. When you slide the tins in the oven the immediate heat jump starts the crust setting and helps the filling thicken. I always wait for the oven to reach the full temperature before baking because a cooler start can make the filling weep. One frequent oversight is opening the oven early to peek which can lower the temperature and affect texture, so avoid opening for the first two thirds of baking time.
Grease a mini muffin tin: Greasing helps with easy removal and prevents sticking on the tin walls, letting you pop out the tarts cleanly once cooled. You can also press a thin strip of parchment into each cavity for extra insurance, which I do when I plan to display them. As you press the dough and fill the tins, greasing ensures edges do not tear when unmolding. A mistake people often make is under greasing, especially in older tins that have rough spots, which leads to stuck corners and broken shells.
For easier removal, you can put a thin strip of parchment paper inside each tin if desired (see photo): Lining with small parchment strips creates a lift point to raise the tarts without inverting the tin, preserving delicate edges. The paper will brown slightly at the edges in the oven and help you slide them out without breaking. If you skip this, be prepared to nudge gently with a small offset spatula. The error to watch for is folding the paper too thickly, which distorts the tart shape, so use thin strips only.
Whisk together the first six ingredients (and 2 tsp spread or oil, if using for a richer flavor): Combining the chopped pecans, water, ground flaxmeal, agave, molasses, and salt creates the filling base, and whisking helps the flax hydrate evenly producing a glossy, cohesive batter. As you whisk you will notice the mixture thicken and darken slightly, and it should hold together when you lift the whisk. The molasses will add a deeper hue and the agave keeps the surface glossy when baked. A common pitfall is under whisking, leaving the flaxmeal clumpy and causing uneven pockets in the filling.
Refrigerate at least fifteen minutes to thicken: Chilling firms the filling so it stays put in the shells and helps flavors meld, producing a more stable, spoonable consistency that bakes into a chewy center. After refrigeration the mixture should be notably thicker and easier to portion into the crust wells. If you skip chilling the filling it may run during baking and not set, resulting in flat, overly sticky tarts. A frequent mistake is refrigerating too long and allowing the filling to become rock hard, so check it after the minimum time.
Meanwhile, combine crust ingredients in a new bowl, completely breaking up the butter until fine crumbles form: Working cold vegan butter into the flour and sugar until it resembles coarse crumbs is crucial to a tender shell, as the discrete bits of butter steam in the oven creating flakiness. As you rub or cut the butter, you will see the mixture go from shaggy to uniformly crumbly. The texture should be sandy and not pasty, which ensures a delicate crust. Overworking the dough so the butter melts will create a dense, greasy shell, so handle it quickly and with chilled tools.
Press 1 1/2 tbsp dough into the bottom of each mini muffin tin, using a spoon or your fingers to make a shallow well in each center: When pressing the dough, aim for an even thickness around each cup, and press a shallow indentation to receive the filling, which ensures uniform baking and consistent ratios of crust to filling. The dough should hold its shape and have a slightly cool feel from the butter. If you press too thin the crust can burn or become brittle; too thick and the tart becomes heavy. An easy mistake is uneven pressing which leads to some shells cooking faster than others, so rotate the tin mid assembly for evenness.
Add about 1/2 tbsp of the refrigerated filling to each well: Portion the chilled filling so each tart gets the same amount, leaving a bit of room for gentle bubbling as it bakes. The filling should sit in the well without overflowing; you may see it glossy and slightly domed before baking. If the filling is still too soft, return it to the fridge briefly to firm up. Avoid overfilling, which will cause spillover and uneven baking.
Bake on the center rack, 12 minutes: Placing the tins on the center rack promotes even heat circulation, helping the crust brown lightly while the filling sets and becomes pleasantly tacky. During baking you will notice the aroma of toasted pecans and a slight bubbling sound as the filling cooks. The edges of the crust should become faintly golden while the filling looks glossy and set. Opening the oven early can cause the filling to collapse, so resist peeking until close to the end of the time.
Let cool before removing from the tins: Cooling allows the filling to finish setting and prevents the shell from breaking when unmolded, leading to clean, intact tarts. Once cooled the edges will firm and the filling will hold shape when you lift them out. If you try to remove them warm they are likely to slump and lose definition, so patience here preserves presentation. A common misstep is forcing removal too soon, which tears the crust.