Preheat oven to 400°F. Grease the muffin tin cups or line with paper muffin liners. If macerating the dried fruit, soak them in coffee liqueur for at least 20 minutes, pressing down the dried fruit occasionally to make sure the top ones get soaked, too.
Make the topping: In a bowl combine the flour, brown sugar, cinnamon, ginger, and salt. Pinch in the butter, or use a pastry cutter, until it looks like coarse crumbs. Mix in the chopped nuts, and then refrigerate topping until ready to top the muffins.
Beat the butter and brown sugar on medium-high until light and fluffy. Beat in the eggs. Stir in the vanilla extract, pumpkin puree, and sour cream or greek yogurt. Drain the dried fruit from the liqueur and stir them into the batter.
Bake for 20-25 minutes or until a toothpick comes out clean when inserted into the middle of the muffins. Allow to cool, then remove from pan. Serve warm or at room temperature.