1. Preheat the oven to 375 F. To make the streusel, combine the almonds, sugar, butter, flour and cinnamon in a food processor and pulse until large crumbs form.
2. In a 9-inch cast iron or other ovenproof skillet, cook the butter and brown sugar over medium heat until melted. Arrange the biscuits in a single layer in the pan; scatter the blueberries over the biscuits and the streusel topping over the berries. Bake until the biscuits are golden and a tester inserted into the center of a biscuit comes out clean, about 30 minutes.
Allow to cool slightly and serve from skillet.