Preheat oven to 350 F/175 C and line three large baking sheets (preferably light-colored metal, like aluminum) with parchment paper or a silicone mat. Set aside.
Whisk together 2 cups + 3 Tbsp (275g) of flour, 1 1/2 tsp baking powder, and 1/2 tsp salt in a large bowl. Set aside.
In a small bowl, add 1/2 cup (100g) granulated sugar and the zest of a large lemon or orange (about 6g). Use your fingertips to massage the zest into the sugar. The rubbing action releases the natural oils from the zest, intensifying the citrus flavor throughout the sugar.
In a large bowl, use a handheld or stand mixer with a paddle attachment to cream together 1/2 cup or 1 stick (113g) of unsalted butter, 2/3 cup (133g) packed brown sugar, and 1/2 cup (100g) of the citrus sugar made in the previous step. Mix on a medium-high speed until the mixture becomes lighter in color.
Then mix in 2 large eggs (112g), 2 tsp (10g) vanilla extract, and 1 tsp lemon or orange extract (optional) on a medium speed. Scrape down the sides and bottom of the bowl as needed with a rubber spatula.
Add the dry ingredients to the wet ingredients and mix on a low speed just until incorporated. The dough should be thick and a little bit sticky!
Divide the dough into four parts. One batch of dough is about 720g, so each portion of dough should be about 180g if you make 4 different colors. Use gel food coloring to make yellow, pink, purple, and green cookie dough.
Combine 2/3 cup powdered sugar and 2/3 cup granulated sugar in a small bowl.
Scoop the dough using a 1 Tbsp cookie scoop, and drop each cookie dough ball directly into the powdered sugar mixture. Be sure to completely coat each cookie and aim to get a thick coating of sugar. Repeat until you've used all the dough. You should end up with 10 cookies in each color and a total of 40 cookies.
Place the cookies on the prepared sheet, spacing them about 2 inches apart. Then lightly flatten each ball to resemble a hockey puck. Bake one sheet of cookies at a time, and bake for 9-10 minutes. Let the cookies cool for 15 minutes on the baking tray before transferring them to a wire cooling rack. Bake time can vary if you make smaller or larger cookies, so keep an eye on them! If desired, top the cookies with some additional lemon/orange zest to really make the flavor pop!
Store any leftover cookies in an airtight container at room temperature for up to 5 days.