Step 1: Brine the Lemon Zest (Optional, but Recommended). In a small bowl, combine the dill pickle brine and water. Add 1 1/2 tablespoons of the lemon zest. Let sit at room temperature.

Step 2: Preheat Oven and Prepare Pan. Preheat the oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners, then coat the liners with cooking spray.

Step 3: Beat Butter and Eggs. Beat the butter and eggs in a medium bowl with a hand mixer on medium-high speed until combined, with small bits of butter remaining, about 3 minutes.

Step 4: Whisk Dry Ingredients. In another medium bowl, whisk the flour, baking powder, baking soda, and salt.

Step 5: Combine Sugar, Milk, and Lemon Zest. In a large bowl, whisk the granulated sugar, milk, and all the lemon zest (brined and regular).

Step 6: Combine Butter Mixture and Sugar Mixture. Add the butter mixture to the sugar mixture and beat with the mixer until combined.

Step 7: Add Flour Mixture. Mix in the flour mixture (switch to a wooden spoon if the batter is too thick for the mixer).

Step 8: Divide Batter. Divide the batter among the muffin cups, filling each about three-quarters full.

Step 9: Bake. Bake until a toothpick inserted into a cupcake comes out clean, 18 to 20 minutes.

Step 10: Cool. Let cool in the pan on a rack for 5 minutes, then remove the cupcakes to the rack and let cool completely.

Step 11: Make the Frosting. Beat 3 cups powdered sugar, the cream cheese, butter, lemon juice, lemon zest, and dill pickle powder with a mixer until light and fluffy; add more powdered sugar as needed to thicken the consistency.

Step 12: Frost Cupcakes. Pipe or spread the frosting on the cooled cupcakes.

Step 13: Decorate (Optional). Top with candied lemon peel and/or finely chopped dill, if desired.