Preheat oven to 350°F (175° C). Grease a 10” (25cm) springform pan and line the bottom with parchment.
In a large bowl combine the flour, sugar, almond flour, cocoa powder, baking powder, baking soda, and salt. Stir to evenly distribute everything.
Create a well in the center and pour in oat milk, coffee, oil, and vanilla extract. Stir until smooth.
Pour into prepared baking pan and shake to level.
Sprinkle the sliced almonds in a single layer over the surface.
Bake for 40-50 minutes until a skewer inserted comes out with just a few crumbs. Cool completely in the pan.
Serve the same day or can be stored at room temperature for up to 3 days. Individual slices can be stored in the freezer (wrapped individually in plastic before being placed in an airtight container) for up to 1 month.
Serve with a dusting of powdered sugar. You can also add a dollop of whipped cream or yogurt (regular or non-dairy).
Notes
Use untoasted almonds on the cake, as pre-toasted ones will dry out and become bitter with the long bake time.
Tap or lightly shake the cake pan once you pour the batter to help remove any lingering air bubbles from the batter.
Wait until the chocolate cake is completely cooled before adding any toppings to it.