Using a 3" heart-shaped cookie cutter, cut the wonton wrappers into hearts (cut 30 hearts to make 15 ravioli, though you may have enough filling to make a few more).: The scent of fresh dough is subtle and slightly sweet as you press the cutter, and the repetitive thud is oddly satisfying, giving you a visual rhythm to the process. You want clean, even hearts so they seal well, and trimming in one comfortable motion helps maintain uniform sizes. Keep unused wrappers under a damp towel to prevent drying, which makes sealing more difficult. A typical slip is trying to cut too many at once and letting the cut pieces sit exposed, which causes cracking along the edges; work steadily and cover them as you go.
Place 1 tsp pesto in the center of one wonton heart.: When the scent of basil and sun dried tomato rises, it tells you the filling is properly seasoned. Place a measured teaspoon into the center so that the filling stays contained and the wrapper can fold around it without bulging. The tactile feedback is important the pesto should sit neatly without touching the edges. A common misstep is using a heaping spoonful, which leads to leaking during cooking; measure carefully to maintain structure.
Dip finger in a small bowl of water and dab around edges of the wonton heart.: The slight dampness should glisten but not drip, creating a tacky sealant for the dough edges. This step smells neutral but feels important under your fingertip as the water primes the gluten to stick. Apply in a thin, even ring to avoid trapping excess moisture between layers. Over saturating the edge will create a soggy seam that fails to adhere, so dab lightly and evenly.
Top with a dry wonton heart and gently press the edges together to seal.: As you press, listen for the faint soft compression of dough and look for a continuous seam without gaps. Patting along the edge helps expel air pockets that can burst in boiling, and a gentle pinch in sections makes a reliable seal. I recommend pressing from one side to the other to move any trapped air outward. Rushing this step or pressing too hard can tear the wrapper, which leads to filling loss in the pot.
Bring a large saucepan of salted water to a boil.: You will smell the faint minerality as the water begins to steam and the surface breaks into rolling bubbles. Use a large pot so the hearts can float freely, preventing them from sticking together. The salt enhances the wrapper and filling flavors, and a vigorous boil helps maintain temperature when you add the ravioli. A frequent mistake is using too small a pot, which causes temperature to drop and leads to clumping and uneven cooking.
Gently place several hearts in the water at a time and cook for 2 – 3 minutes.: As they cook, watch for the wrappers to look translucent and slightly plump, and notice a softer, more tender feel when you nudge them with a spoon. The brief cook time preserves the fresh herb brightness and gives a pillowy texture, while overcooking makes the wrapper mushy and prone to breakup. Avoid dropping too many at once or stirring aggressively, both of which can cause tearing or sticking; add them in small batches for best results.
Remove ravioli hearts from water with a slotted spoon and transfer to a plate.: The gentle clink of the metal spoon and the sight of glossy, tender hearts on the plate is very satisfying. Draining with a slotted spoon keeps them intact and prevents them from soaking in residual water, which would dilute flavor. Transfer in a single layer if possible to avoid crushing, and use a shallow plate to keep them warm. A common error is piling them too high which causes steaming and sogginess; arrange them with space between each piece.
Sprinkle with parmesan cheese and serve immediately.: The aroma of freshly grated Parmesan Cheese hitting warm pasta lifts the whole dish, creating a salty, nutty finish that balances the pesto. The cheese clings to the warm surface, adding both flavor and a pleasing textural note. Serve right away so the contrast between warm filling and the slightly cooler air is at its best. Leaving them to sit will let moisture redistribute, softening the edges and reducing the textural pop that makes these delightful.