Step 1: Preheat & Prep

• Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.

Step 2: Cream Butter & Sugar

• In a large bowl, beat the butter and sugar together until light and fluffy, about 2–3 minutes.

Step 3: Add the Egg and Flavor

• Mix in the egg, lemon juice, lemon zest, and vanilla (if using). Beat until smooth and fully combined.

Step 4: Combine Dry Ingredients

• In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry mixture to the wet ingredients, mixing just until combined.

Step 5: Fold in Blueberries

• Gently fold in the blueberries, being careful not to overmix, especially if using frozen berries to avoid color bleeding.

Step 6: Scoop and Bake

• Drop rounded tablespoons of dough onto your prepared baking sheets, spacing them about 2 inches apart. Bake for 10–12 minutes, or until the edges are lightly golden and the centers are set.

Step 7: Glaze and Cool

• Let cookies cool on the sheet for 5 minutes, then transfer to a wire rack. If glazing, whisk together powdered sugar and lemon juice until smooth and drizzle over the cooled cookies.