Preheat the oven to 375 degrees F. Spray a doughnut hole pan liberally with nonstick spray.
Whisk together the flour, sugar, baking powder and salt in a medium bowl. In a second bowl, whisk the butter, vanilla and egg until smooth; then whisk in the 1/2 cup milk and the lemon zest until combined. Add the wet ingredients to the dry, and mix until a batter just comes together. Cover and let sit at room temperature for 15 minutes.
Fill the molds of the prepared doughnut hole pan two-thirds of the way with batter, then press a few blueberries into each. Bake until lightly golden brown, about 10 minutes. Flip and bake another 3 to 4 minutes.
Mix together 1/2 cup of the confectioners' sugar and the remaining 1 to 2 teaspoons milk to make a glaze. Toss some of the pancake bites in the remaining confectioners' sugar.
Serve drizzled with the glaze, or serve with warm maple syrup for dipping.