Preheat the oven to 350°F. Grease an 8”x4” loaf pan with pan release on the bottom and up the sides. I recommend using cake goop! Or you can line the bottom and sides with parchment paper to easily flip it out later. You can also use an 8”x8” nonstick square cake pan, it will just take less time to bake. If you want to use a larger bundt pan, make 1 and a half batches of this recipe. Make sure your butter, sour cream, egg, and cream cheese are all room temperature so that the ingredients combine together well. I place my eggs (still in the shell) into a bowl of warm water for a few minutes and leave out the butter and sour cream for a few hours. If needed, I microwave them for a few seconds until they are room temperature or even slightly warm.
Place the butter and granulated sugar into the bowl of your stand mixer with the whisk attachment. Mix on medium-high speed and cream together until light and fluffy, about 2-3 minutes. (Or longer if you’re using a hand mixer.)
Add your egg, sour cream, and vanilla to the creamed butter and mix until cohesive. If it has big chunks of cold butter in there, one of your ingredients was too cold.
Add in the flour, baking soda, baking powder, and salt. Mix on medium-low speed until the batter is thick and just combined. If your flour is really lumpy, sift these dry ingredients before adding them to the mixer.
Place half of the batter into the greased loaf pan and smooth it out in an even layer.
Sprinkle the cinnamon sugar filling on top until it’s completely covered.
Add the rest of the cake batter on top.
Sprinkle the thick crumbs evenly on top, covering the surface of the loaf.
Bake at 350ºF for 40-50 minutes and rotate halfway through for even baking. When a toothpick comes out clean from the center, it’s done!
Rest the loaf at room temperature until the pan is completely cool, about 2 hours. Do NOT flip your cake out while it’s warm, it could collapse.
Loosen the edges with a knife, place a piece of plastic wrap on top of the cake, and flip it upside down to remove it from the pan.