Preheat the oven to 375°F. Line a 9x9-inch square pan (or a 9-inch round pan) with parchment paper, leaving a little overhang on the sides.
Mix the dry ingredients: In a large bowl, combine flour, oats, baking powder, salt. Stir to combine.
1 ½ cup all purpose flour, 2 cups quick cooking oats, ½ teaspoon baking powder, 1 pinch of salt
Add the butter: Drop in the room temperature butter and knead it into the dry ingredients with your hands until the mixture starts to form soft dough.
1 cup + 2 tablespoon butter
Add sugar, zest, vanilla, and nuts: Stir in the brown sugar, lemon zest, vanilla extract, and chopped pecans (reserve 3 tablespoon of nuts for the topping).
¾ cup brown sugar, 1 tablespoon lemon zest, 1 teaspoon pure vanilla extract, ¾ cup pecans
Form the base: Pinch together small dough balls, about cherry-size. Place two-thirds of them into the baking dish and press to form an even bottom layer.
Add the raspberries: Spread the fresh raspberries over the dough base.
10 ounces fresh raspberries
Top and bake: Sprinkle with the remaining pecans and gently press them down. Bake for 35–40 minutes, or until the top is lightly golden.