Preheat the oven to 350-degrees. Grease a 9×13 pan with butter.
In a large mixing bowl, add the oats, flour, sugar, baking powder, salt and cinnamon. Stir to combine. Add the butter and use a fork to cut it into dry ingredients until the mixture resembles coarse meal and is no longer powdery. You’ll still be able to see some of the butter, but that’s ok.
Set aside about half of the oat mixture; press the rest firmly into the prepared pan. Now you want to partially bake it until lightly browned at the edges, 13 to 15 minutes.
Remove from the oven and carefully spread strawberry preserves over the partially baked oat layer. Sprinkle with reserved oat mixture. Bake until topping is slightly browned, 20 to 25 minutes. Set the pan on a rack to cool completely before cutting.