In a medium bowl, combine ½ cup brown sugar, ⅓ cup flour, and 1 teaspoon cinnamon. Add the cold diced butter and mix with your fingers until the mixture resembles coarse crumbs. Set this aside.

In a large mixing bowl, mix together 1 cup flour, 2 tablespoons brown sugar, baking powder, baking soda, and salt.

In another bowl, whisk together the buttermilk, egg, and melted butter until smooth. Combine the wet ingredients with the dry ingredients until just blended.

Heat a non-stick skillet or griddle over medium heat. Lightly grease it with butter.

Pour about ¼ cup of batter for each pancake onto the skillet and sprinkle a generous spoonful of the streusel topping on top of the uncooked batter.

When the edges start to look firm and you see bubbles forming, flip the pancakes and cook for another minute or so until golden brown.

Stack the pancakes high on a plate, drizzle with syrup, and add a dollop of whipped cream if desired.