Preheat oven to 375°F.
In a saucepan, brown 1 stick of butter over medium-high heat, stirring often. Let cool.
In a large bowl, whisk browned butter, 2 eggs, 1¼ cup brown sugar, 1 cup pumpkin purée, ½ cup Greek yogurt, 1 tbsp vanilla.
In another bowl, mix 2 cups flour, 1 tbsp pumpkin pie spice, ½ tsp salt, 1 tsp baking soda, 1 tsp baking powder.
Fold dry ingredients into wet.
Make crumble: mix 1½ cups brown sugar, 1½ cups flour, 1 stick softened butter, 1 tbsp cinnamon, 1 tsp salt with a fork until crumbly.
In an 8x8 pan, layer half the batter, crumble, then the rest of the batter, and top with crumble.
Bake 45 minutes.
Glaze: mix ⅔ cup powdered sugar, 1 tbsp maple syrup, 1 tsp vanilla, pinch of salt. Drizzle on top.
