"The flavor of the caramelized butter really makes this crisp unique. While baking, it will fill your house with the most delicious aroma. Use whatever berry combination you desire. Tastes amazing with whipped cream, ice cream, or a big dollop of Greek yogurt."
Preheat oven to 350 degrees F (175 degrees C). Butter a 9-inch pie dish.
Melt butter in a small saucepan; bring to a low simmer and cook, stirring frequently, until butter is browned, fragrant, and foamy, with browned bits in it, 5 to 10 minutes. Cool to room temperature, about 15 minutes.
Combine white sugar, cornstarch, lemon zest, lemon juice, and vanilla extract in a bowl. Add thawed berries and toss gently. Transfer berry mixture to the bottom of the greased pie dish.
Combine flour, oats, brown sugar, baking soda, baking powder, and salt in another bowl. Stir in 1/2 cup browned butter until mixture is evenly wet and crumbly. Spread evenly over top of berry mixture.
Bake in the preheated oven until golden brown, 35 to 40 minutes. Remove from oven and allow to cool slightly before serving.