For the streusel topping: Combine the almonds, sugar, butter, flour, and cinnamon in a food processor and pulse until large crumbs form.

For the coffee cake: Preheat the oven to 375 degrees F.

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 skillet. Scatter the blueberries over the biscuits, and then distribute the streusel topping over the berries. Bake until the biscuits are golden and a tester inserted in the center of a biscuit comes out clean, about 30 minutes. Allow to cool slightly and serve from the skillet.