Preheat your oven to 350°F and grease a 24-cup muffin tin (or two 12-cup tins). In a medium bowl, whisk together the flour, baking powder, baking soda, and salt, then set aside. Prepare your shredded yellow squash by finely shredding it with a box grater or food processor, then place it in a clean kitchen towel and squeeze firmly to remove as much moisture as possible—this prevents the muffins from becoming soggy. Have all your other ingredients measured and ready, with eggs at room temperature for better emulsification.

In a large mixing bowl, whisk together the sugar, oil, lemon extract, and room-temperature eggs until the mixture is well combined and pale, about 1-2 minutes. The oil and sugar create an emulsion that keeps the muffins tender. Stir in the lemon juice and lemon zest, then fold in the sour cream gently until just combined—I like using Daisy brand sour cream because its thicker consistency helps maintain the muffin structure better than thinner varieties.

Add the squeezed-dry shredded squash to the wet ingredient mixture and fold it in gently until evenly distributed. Pour the dry ingredient mixture from Step 1 over the wet ingredients and fold everything together with a spatula until just combined—do not overmix, as this will develop gluten and create tough muffins. The batter should look thick and slightly lumpy, which is exactly what you want.

Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full. Bake at 350°F for 22-25 minutes, until a toothpick inserted into the center of a muffin comes out with just a few moist crumbs—don't overbake or they'll become dry. The muffin tops should be golden brown and slightly domed.

While the muffins are baking, prepare the glaze by sifting the powdered sugar into a small bowl to remove any lumps. Whisk in the vanilla extract, freshly squeezed lemon juice, and a pinch of fine salt until you have a smooth, pourable consistency—it should be thick enough to coat a spoon but thin enough to drizzle. I always use freshly squeezed lemon juice for the glaze because the bright, tangy flavor really makes a difference in the final taste.

Remove the muffins from the oven and let them cool in the pan for 2-3 minutes, then turn them out onto a wire cooling rack. While the muffins are still warm (but not piping hot), drizzle or spoon the lemon glaze over the tops, allowing it to run down the sides slightly. Let the muffins cool completely on the rack before serving, which allows the glaze to set and the flavors to meld together beautifully.