Preheat your oven to 350 F. Grease an 8x11 baking dish and line with parchment, letting the excess hang over the sides (you’ll use this to pull the cake out of the pan).
In a medium bowl, whisk together the flour, oats, brown sugar, cinnamon, nutmeg and sea salt. Using a pastry blender or your hands, work the butter into the mixture until it resembles wet sand and when pinched together it holds into clumps. Gently mix in the almonds and place in the fridge. If storing overnight, cover with plastic wrap; otherwise it’s fine for an hour-ish.
In an electric stand mixer fitted with the paddle attachment (or use a bowl and spoon) mix the butter and sugar on medium until light and fluffy or about 5-6 minutes. You want it pretty fluffy, so if your kitchen is chilly let the machine run longer. Scrape down the sides and bottom of the bowl to make sure everything is the same consistency. Add in the eggs, one at a time, making sure the first is well blended before adding in the second. Add in the vanilla and run the machine for 1 minute more.
In a medium bowl whisk together the cake flour, cinnamon, baking powder, baking soda, salt and then add half to the mixer and run the machine until it’s almost blended. Add in half of the milk and run the machine until almost blended. Repeat with the remaining flour mixture and milk.
Scoop the mixture into the prepared pan smoothing the top a bit with the back of a spoon/spatula so that it’s even. Sprinkle with 3/4ths of the cherries, cover with the streusel (there’s a lot!) and then sprinkle with the remaining cherries.
Bake in the center of the oven for 50 minutes. The center will be soft, maybe a slight jiggle, but set. The top and exterior should be nicely bronzed. Let cool on a cooling rack for 15 minutes and then use the parchment handles to remove it from the pan so that it can finish cooling out of the pan. If it resists coming out run a knife around the edge to help it along. Additionally, you can let it cool longer in the pan if you’re having a hard time getting it out. Don’t stress.
While the cake cools, whisk up your powdered sugar and milk to make the drizzle. You want it pretty thick so the bright white shows up over the top and then drizzle it all Jackson Pollock like over the top. Cut and serve.