Preheat oven to 375°F.
In a medium bowl, combine the oats, granola, 3 tablespoons flour, and brown sugar. Cut in the 1/4 cup butter until crumbly.
Place peach slices in an 8-inch square baking dish. Sprinkle with remaining 1 tablespoon flour. Scatter the oat mixture over the peaches. Sprinkle top with cinnamon, nutmeg, allspice, and pecans.
Bake in preheated oven for 30 minutes, or until golden brown.