• Preheat oven to 375F (190C) and line a 12-count muffin tin with paper liners. Set aside.
• Combine your melted butter and canola oil in a large bowl. Stir well.
• Add sugar and stir to combine.
• Add egg, egg white, and vanilla extract. Stir very well, until all ingredients are thoroughly combined.  Add buttermilk and stir.
• In a separate, medium-sized bowl, whisk together flour, baking powder, corn starch, cinnamon and salt.
• Using a spatula, gently fold the dry ingredients into the wet, taking care not to over-mix the batter (which will make your muffins dense and tougher).
• Evenly divide the batter into prepared muffin tin, filling each liner about 2/3 of the way full. Set aside and prepare your streusel topping.

Streusel

• Prepare your streusel by whisking together flour, sugars and cinnamon.
• Pour the melted butter into the mixture and, using a fork, stir until crumbles form. 
• Using your hands, evenly divide streusel over muffin batter, piling the streusel over the batter and gently pressing the topping into the batter.
• Bake on 375F for 22-25 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
• Allow to cool before serving.