Preheat your oven to 350°F (175°C). Grease and line a 9x13-inch baking pan with parchment paper, leaving some overhang for easy removal.
In a large mixing bowl, combine the all-purpose flour, granulated sugar, baking powder, and salt. Mix well.
Add the softened butter, eggs, vanilla extract, and milk to the dry ingredients. Beat with an electric mixer on medium speed until the batter is smooth and well combined, about 2-3 minutes.
Pour half of the batter into the prepared baking pan and spread it evenly. Spoon the raspberry jam over the batter, spreading it gently to cover.
In a separate bowl, mix the almond flour and almond extract into the remaining batter until combined. Spoon this mixture over the jam layer and spread it evenly.
Sprinkle the sliced almonds on top of the batter.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool in the pan for about 10 minutes before lifting it out using the parchment paper.
Once completely cool, cut into squares and serve.