Preheat oven to 350°F and line a large baking sheet with parchment paper.
Using a handheld mixer at medium-high speed, add the butter and sugars. Cream for 2-3 minutes, or until they are fully incorporated and fluffy.
Add in the eggs and vanilla and mix until combined.
Add in the flour, oats, baking soda, and cinnamon. With the mixer on low, mix until just combined.
Gently fold in the frozen raspberries.
Use a cookie scoop (1½ tablespoons) and drop the dough onto the baking sheet about 2 inches apart.
Bake for 8-10 minutes, or until the edges are lightly golden. The tops of the cookies may appear a little wet, but they will continue to bake out of the oven. On the other hand, you don't want the cookies raw, so make sure they bake for at least 8 minutes.
Let the cookies rest for 5-10 minutes before enjoying.