Preheat the oven to 350°F (175°C) and grease and flour your loaf pan.
Cream together 1 cup of ricotta cheese, 1 cup of granulated sugar, and 1/2 cup of softened unsalted butter in a mixing bowl until smooth.
Add the 3 large eggs one at a time, mixing well after each addition, then stir in 1 teaspoon of vanilla extract.
Whisk together 1 cup of all-purpose flour, 1/2 cup of unsweetened cocoa powder, 1 teaspoon of baking powder, and 1/2 teaspoon of salt in another bowl.
Combine the dry ingredients gradually into the wet mixture, stirring until just combined.
Divide the batter in half and stir 1/2 cup of melted semi-sweet chocolate chips into one half.
Spoon alternating dollops of both the plain and chocolate batter into your prepared loaf pan.
Swirl the batters together gently with a knife.
Bake in your preheated oven for about 45-50 minutes or until a toothpick inserted into the center comes out clean.
Cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.