FOR THE TOPPING
Rub flour, brown sugar, almonds and butter with fingertips until clumps form.
FOR THE MUFFINS
Preheat the oven to 400 degrees . Line a 12-cup muffin pan with 1 1/4-inch paper liners. In a bowl, whisk the flour, baking powder, cardamom and salt. Stir in berries. In a large bowl, whisk the buttermilk, oil, sugar, almond extract and eggs. Add the dry ingredients to the wet mixture and fold until just barely blended.
Divide the batter among the liners (fill about three-quarters); top with crumbled mixture. Bake until puffed and golden brown and a toothpick inserted into the center comes out clean, 13 to 17 minutes. Cool in the pan.