Preheat oven to 180°C | 360°F.: The air in the oven should feel dry and warm when you open the door, signals that the environment will coax a steady rise and even browning. You will notice a light heat shimmer and a faint metal scent as the racks warm, which means the leaveners will react predictably when the batter hits the oven. Preheating is critical because putting batter into an oven that is not at temperature often yields flat, dense tops instead of domed muffins. A common mistake is rushing this step, so always allow the oven to reach temperature fully before baking.
Spray 2 muffin trays with spray oil and wipe over with paper towel.: When you spray and then wipe the cups, you create a thin, even barrier that prevents sticking but avoids an oily puddle at the bottom. You might hear a faint sizzle when the warm tray meets the batter later, and the paper towel wipe helps the batter cling for a clean release. If you skip wiping, excess oil can pool and fry the bottoms, causing uneven texture. Err on the side of a light coating, especially if you want tidy muffins.
In a large sized bowl, mix together all wet ingredients.: As you whisk the mashed bananas , melted butter , honey , vanilla , egg , egg whites , apple sauce , and almond milk , you should see a homogenous, slightly glossy batter with streaks of banana. The aroma will be sweet and fragrant, and the texture should be silky. Blending the wet ingredients first ensures even distribution of moisture, which helps the dry ingredients hydrate properly. Overbeating here is less risky than overworking after adding flour, but vigorous whisking can incorporate too much air leading to overly domed, cracked tops.
Add dry ingredients, mixing again, but be careful not to over beat the batter.: Once you combine the spelt flour , baking powder , baking soda , cinnamon , and natural sweetener into the bowl, fold gently until just incorporated. The batter should be lumpy and thick but pourable, not smooth like cake batter. You'll hear a muted plop as the spoon moves through it, and the mixture will lose any streaks of flour. The reason for gentle mixing is to avoid developing too much gluten, which would make the muffins tough. A common misstep is beating until perfectly smooth, which actually ruins the tender crumb you are aiming for.
Fold in blueberries and chocolate chips.: Gently folding in blueberries and chocolate chips keeps them intact so they punctuate the crumb rather than coloring the entire batter. You want to see clusters of blue and flecks of chocolate, not a uniformly purple hue. The sound is soft and the batter should look marbled in places. If you stir too hard you will break berries and make the batter runny, which can cause uneven baking and soggy pockets.
Pour 1/4 cup batter per muffin into each muffin cup and top with extra chocolate chips.: Using a 1/4 cup measure ensures consistent muffin sizes, so they bake evenly and finish at the same time. The batter should slide smoothly into each cup and sit slightly mounded. Placing extra chocolate chips on top creates glossy, melted crowns when they warm, and gives a professional finish. If you overfill, the muffins will spill over and bake irregularly, so keep the measure consistent for tidy results.
Bake in pre-heated oven for approximately 25 - 30 mins, or until muffins are golden brown on top and cooked through when tested with a toothpick.: During baking you will notice the tops rise and take on a golden tone, with the aroma of sweet banana and chocolate filling the kitchen. The edges will become slightly firmer and the centers spring back when touched gently. The toothpick test should come out with a few moist crumbs but not wet batter. Baking too long dries them out, while underbaking leaves gummy centers, so monitor closely starting at the 25 minute mark and remove once the pick test is right.