Melt the butter. Set it aside to cool for about 15 minutes. Preheat oven to 350 ℉. Line two baking sheets with parchment paper. Set aside.
If adding walnuts, spread them on a baking sheet. Bake at 350 for 8-10 minutes, til fragrant. Once cooled, chop the walnuts and set them aside.
If using wild blueberries, leave them in the freezer for now. If using regular sized frozen blueberries, take them out of the freezer. Measure out 1 cup or 100 grams then immediately chop them. Place the chopped blueberries in a bowl and place them in the freezer immediately til when you're ready to add them to the cookie dough.
In a medium sized bowl, whisk to combine the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, add the granulated sugar and lemon zest. Use your fingertips to rub the zest into the sugar. This helps to bring out the lemon flavor. Add the brown sugar and cooled butter. Whisk the mixture together til completely combined.
Add the egg followed by the yolk and mix until just combined. Add the vanilla extract and the optional almond extract (if using).
Add the dry ingredients to the wet ingredients. Stir with a spatula until just combined. Do not overmix. Take the frozen chopped blueberries out of the freezer and immediately add them and the cooled, chopped nuts (if using) to the cookie dough. Very gently stir in the blueberries (and nuts) until just combined.
Form the dough into 2 tablespoon sized balls. I use a #24 cookie scoop. Place on a baking sheet about 2 inches apart.
Bake 12-14 minutes or until edges turn golden brown and the tops look puffed up but set.
Allow to cool slightly on the baking sheet for 10 minutes then transfer to a rack to cool completely.
Video
Notes
Lemons: This recipe calls for the zest of 2 medium lemons. We are only using the zest. You won't need any lemon juice for the recipe. Blueberries: Use fresh or frozen. If using frozen, do not thaw them or leave them out at room temperature — the juice will bleed through the dough. You can use wild frozen blueberries or regular frozen blueberries. Chop them into various sizes (between a rough and small chop) then place back in the freezer until you're ready to add them. If using fresh blueberries, no chopping needed — just fold them in as is. Whether using fresh or frozen, fold them into the dough just until incorporated, then scoop and bake immediately. Keep the remaining dough in the fridge while each sheet bakes.Almond extract (optional): We're only adding 1/4 teaspoon so it doesn't give a strong almond flavor. It does, however, add to the overall deliciousness of these cookies! Nuts (optional): I recommend adding between 1/3 cup or up to 1/2 cup of chopped toasted nuts. I like walnuts here, but almonds, pistachios, or hazelnuts would also be delicious. I highly recommend toasting the nuts. It enhances the flavor and gives the nuts even more of a crunch. Toast nuts whole then allow to cool then chop them. Oven temperature: Always check your oven temperature before the first batch and between batches. Opening and closing the door causes the heat to drop, so give it a few minutes to heat back up before adding the next tray.Storage: Store these lemon and blueberry cookies at room temperature in an airtight container for 2-3 days. These cookies are best the day they're made. They will soften a bit more than other cookies because of the blueberries. Freeze leftover cookies for up to 30 days. Thaw at room temperature or in the refrigerator.
Nutrition Information: The nutrition information provided is an estimate. The calorie accuracy is not guaranteed.