Preheat oven to 350°. Grease or line baking sheets.
Whisk together flour, baking soda, cinnamon, and salt. Set aside.
Beat butter and both sugars until light and fluffy. Add eggs, one at a time, mixing well after each addition. Mix in vanilla. Gradually add flour mixture, mixing until fully incorporated. Mix in oats.
Scoop dough onto prepared pans, placing them about 2 inches apart. Using your thumb, make a hollow in each cookie. Fill each hollow with jam (or preserves).
Bake 12-14 minutes, until cookies are fully baked and the edges are golden.