3 1/3 cups pastry flour
1 tsp kosher salt
½ tsp baking powder
¾ cup sour cream
½ cup canola oil
3 Tbsp honey
1 Tbsp vanilla extract
½ cup almond paste
6 large eggs, beaten
1¼ cups unsalted butter, soft
1¼ cups granulated sugar
2 cups Oatmeal Streusel (recipe here)
Preheat the oven to 350°F. Prepare an 11×17-inch jelly roll pan by spraying it lightly with cooking spray or lining with parchment paper. Dust it lightly with flour, shaking out any excess.
In a large bowl, sift together the flour, salt, and baking powder. Set aside. In another small bowl, blend the sour cream, oil, honey, and vanilla extract. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream the almond paste with two tablespoons of the beaten eggs on medium speed until smooth and light, two to three minutes. Scrape down the bowl to blend evenly. Add the butter and sugar and continue to mix until very smooth and light, about two minutes more.
Add the remaining beaten eggs in three additions, mixing until smooth and scraping down the bowl after each addition. Scrape down the bowl to blend evenly.
Add the flour mixture to the creamed butter mixture and mix the batter until it is evenly blended, scraping down the bowl as needed. Fold in the sour cream mixture by hand with a rubber spatula until just combined.
Spread the batter in an even layer in the prepared jelly roll pan. Sprinkle the streusel evenly over the top of the cake. Bake until a toothpick inserted into the center of the cake comes out clean and the cake edges are golden brown, about 30 minutes.
Cool the cake in the pan on a wire rack. When the cake is completely cool, slice and serve it or wrap well in plastic wrap and store at room temperature for up to three days or in the freezer for up to six weeks.