Preheat oven to 350°F (175°C)
Line baking sheets with parchment paper
In a large bowl, cream softened butter and sugar until light and fluffy
Add egg, lemon juice, and lemon zest; mix until fully incorporated
Fold in vanilla extract and optional lemon extract
In a separate bowl, whisk together oat flour, cornstarch, baking soda, baking powder, and salt
Gradually add dry ingredients to wet mixture and mix until just combined
Fold in thawed and patted-dry raspberries
Using a small ice cream scoop, portion dough into 1.5-inch rounds, spacing them 2 inches apart
Bake for 10-12 minutes until edges are golden and centers are set
Allow cookies to cool on baking sheets for 5 minutes before transferring to wire racks