2 cups all-purpose flour
2 teaspoons corn starch
1/2 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
1/4 cup butter, melted and cooled
1/4 cup canola oil
1/2 cup sugar
1/2 cup brown sugar
2 large eggs
1 cup pumpkin puree
1/2 tsp vanilla
1/4 cup sour cream

Crumble:
6 tablespoons butter, chilled
1/2 cup sugar
1/2 cup brown sugar
1/2 cup flour
2 teaspoons ground cinnamon
3/4 teaspoon ground nutmeg
1/2 teaspoon ground cloves
1/2 teaspoon ginger
1/2 teaspoon salt