HEAT oven to 375 degrees F. Combine 1 1/2 cups flour, nuts, granulated sugar, brown sugar and 1 teaspoon cinnamon in medium bowl. Add butter; mix until mixture resembles coarse crumbs. Reserve 1 1/4 cups crumb mixture. Pat remaining mixture on bottom of ungreased 13 x 9-inch baking pan.
COMBINE pumpkin, sweetened condensed milk, eggs, remaining 1 teaspoon cinnamon, allspice and salt in large bowl; mix well. Pour evenly over crust.
MIX reserved crumbs with remaining 1 tablespoon flour. Sprinkle over pumpkin mixture.
BAKE 30 to 35 minutes or until set. Cool 10 minutes. Serve warm.