Small Batch Pumpkin Coffee Cake

Moist pumpkin spice cake loaded with two layers of pumpkin spice streusel.

Butter an 8×4" loaf pan, then line it with parchment paper to form a sort of hammock, where there are two sides with parchment paper sticking up. This will make it easy to pull the loaf out of the pan when it's done baking.
Preheat the oven to 350°F / 175°C.
In a medium sized bowl, melt the butter. Add in the flour, sugar, and pumpkin pie spice. Use a fork to mix the ingredients together until you have formed little clumps of dough. Set aside.

In a medium sized mixing bowl, melt the butter in 20 second intervals until it fully melts, then mix in the brown sugar.
Add in the egg, vanilla, pumpkin puree, and sour cream. Whisk vigorously until the mixture is cohesive and well combined.
Add in the flour, baking powder, salt, and pumpkin pie spice. Fold the dry ingredients into the wet ingredients just until no flour streaks remain.
Add half of the cake batter to the prepared loaf pan, and top it with ~1/3 of the streusel. Top the streusel with the remaining batter, then top the batter with the remaining streusel.
Bake for 35-45 minutes, until a toothpick inserted in the center of the coffee cake comes out with just a few moist crumbs.

In a small bowl, whisk together the powdered sugar and milk. If you'd like a thicker glaze, add more powdered sugar. If you'd like a thinner glaze, add more milk.
Once the cake has cooled to room temperature, top it off with the glaze, serve, and enjoy!