Prepare the Cake:

Preheat Oven: Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or line it with parchment paper.

Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

Cream Butter and Sugar: In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy.

Add Eggs and Vanilla: Beat in the eggs one at a time, then stir in the vanilla extract.

Combine with Buttermilk: Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk, starting and ending with the dry ingredients. Mix until just combined.

Fold in Blueberries: Gently fold in the blueberries, being careful not to crush them.

Pour into Pan: Pour the batter into the prepared cake pan and smooth the top.

Prepare the Topping:

Mix Topping Ingredients: In a small bowl, combine the sugar, cornstarch, lemon juice, and cinnamon. Sprinkle this mixture evenly over the top of the cake batter. If using, add sliced almonds for extra crunch.

Bake the Cake:

Bake: Bake in the preheated oven for 40-45 minutes, or until a toothpick inserted into the center comes out clean.

Cool: Once baked, remove the cake from the oven and allow it to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.

Serve:

Slice and Enjoy: Once cooled, slice the cake and enjoy it plain or with a dollop of whipped cream for a delicious dessert!