Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, cream together butter, sugar, and lemon zest. Rub zest into sugar first for extra flavor.
Add eggs and vanilla. Beat until smooth and fluffy.
In a separate bowl, whisk together flour, cornstarch, baking soda, and salt.
Gradually mix dry ingredients into the wet mixture until just combined.
Gently fold in raspberries using a spatula. Handle with care to avoid breaking them.
Scoop dough into even portions using a cookie scoop and place on prepared baking sheets.
Bake for 10–12 minutes, rotating pans halfway through.
Cookies are done when edges are set and centers look slightly underbaked.
Cool on baking sheet for 5 minutes, then transfer to a cooling rack.
Optional: Drizzle with lemon glaze once completely cooled.