In a small mixing bowl, combine the flour, oats, brown sugar, butter, and cinnamon. Use a fork to mix just until combined. Refrigerate while you prepare the filling.
In a separate large mixing bowl, combine the pumpkin puree, eggs, evaporated milk, sugars, and spices. Mix by hand or using a hand mixer until completely combined. Pour the filling into a greased 8×11 inch baking pan.
Remove the topping from the refrigerator and crumble it gently over the filling in the pan. Bake at 375°F for 45-50 minutes, until the topping is dark golden brown and crispy.
Remove from oven and cool slightly before serving. Top with ice cream or whipped cream as desired.
Notes
Recipe Variations
Substitute pumpkin pie filling for pumpkin puree and omit the brown sugar, granulated sugar, vanilla, pumpkin pie spice, and salt
Replace all purpose flour with any flour you prefer (make it gluten free by using gf flour)
Substitute quick oats for rolled oats
Double the topping for even more of that delicious crisp flavor
Bake it into individual crisps using a muffin tin and cupcake liners (reduce baking time accordingly)