Preheat oven to 375°F (190°C). Line a jumbo muffin tin with 6 liners or 12 standard size liners.

Make streusel: In a bowl, mix flour, brown sugar, and cinnamon. Cut in cold butter with a fork or fingers until crumbly. Chill until ready to use.

Mix dry ingredients: In a medium bowl, whisk flour, baking powder, baking soda, salt, and spices.

Mix wet ingredients: In a large bowl, whisk melted butter, oil, sugars, eggs + yolk, buttermilk, and vanilla until smooth.

Combine: Gently fold dry into wet, mixing just until combined (don’t overmix).

Fill tins: Divide batter into liners (they’ll be very full). Sprinkle generously with streusel.

Bake: 15-20 minutes, or until a toothpick comes out with a few moist crumbs and tops are puffed up. Remove from pan and cool slightly.

Make glaze: Beat cream cheese until smooth. Add powdered sugar, vanilla, milk or heavy cream and lemon juice and zest to desired consistency. Drizzle over cooled muffins and enjoy!