Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan.

In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, and salt until well combined.

In another bowl, mix the milk, melted butter, eggs, and vanilla extract. Gradually add this mixture to the dry ingredients, stirring until just combined.

Pour half of the batter into the prepared baking pan and spread it evenly.

In a separate bowl, combine the ricotta cheese, powdered sugar, lemon zest, and almond extract. Mix until smooth.

Spoon the ricotta mixture over the batter in the pan, spreading it gently to cover as much as possible.

Pour the remaining batter over the ricotta layer, spreading it carefully to avoid disturbing the ricotta.

If using, sprinkle the chocolate chips on top of the batter.

Bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Once cooled, slice into squares and serve.