Preheat oven to 350 degrees F. Grease a 9 inch spring form pan and line the bottom with parchment paper.
Make frangipane by combining all frangipane ingredients in a bowl. Stir until well combined. Set aside.
In a glass liquid measuring cup, make the vegan buttermilk by combining the almond milk and lemon juice or vinegar. Set aside.
In a medium mixing bowl, make the flax egg by combining the ground flaxseed and water. Stir and set aside for 5 minutes to thicken.
In a large bowl, add the flour, baking powder, baking soda, and salt. Whisk until well combined.
In the medium bowl with the flax egg, add the melted butter, sugar, yogurt, vegan buttermilk that you made, vanilla extract, and almond extract. Whisk until well combined.
Add the wet to the dry. Stir with a spatula until just combined. Don’t overmix it. Fold in the blueberries leaving about 3/4 cup for the topping (make sure you toss the blueberries in 2 Tbsp of flour before adding it to the batter). Careful not to overmix again.
Pour batter into the lined pan. Take frangipane and spread evenly on top of the batter. Place the reserved blueberries on top of the frangipane. Sprinkle sliced almonds all over the top. Bake in the oven for 60 minutes or until a toothpick comes out clean and the top is golden. Let it cool in the pan for 15 minutes, then carefully transfer the cake out of the pan and let it cool on a wire rack. Slice and enjoy! Store leftovers in an airtight container on the counter for up to 3 days.