1Preheat the oven to 350F.
2In the bowl of a food processor, pulse the flour, almonds, sugar and salt until well blended and the nuts are finely ground. Add the butter and vanilla or almond extract and pulse until well combined and crumbly. The mixture should hold together when you squeeze it.
3Divide a little more than half the mixture between two 8 or 9-inch cake pans, 8x8-inch pans, fluted tart pans or one 9x13-inch pan. Press evenly into the bottom of the pan. Spread with mincemeat, preserves, or whatever you want to top it with, then sprinkle the rest of the crumble mixture overtop, squeezing slightly as you go. Bake for 30 minutes, or until pale golden around the edges and set.
4Cool before cutting into wedges or squares.