Preheat your oven to 350°F (175°C) and grease your 9-inch round cake pan.
In a mixing bowl, combine the butter and granulated white sugar. Cream them together until light and fluffy.
Add the large egg and almond paste to the creamed mixture. Beat until well combined.
Gradually add the all-purpose flour to the mixture. Stir gently until just combined.
Gently fold in the sliced almonds with a spatula.
Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes.
Once baked, let the cake cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.
