Chocolate Ricotta Muffins

This is one more recipe I tried from the book from the library and absolutely loved it !!! Ricotta is a sweet, moist and grainy soft textured cheese that gives these Chocolate Ricotta Muffins a cheesecake-like taste and texture. They provide a double dose of chocolate; one from cocoa powder and the other from chocolate chips. 
1 cup ricotta cheese
2 large eggs
1 1/3 cup (320 ml) milk
1 tablespoon pure vanilla extract
4 tablespoons (57 grams) unsalted butter melted and cooled
2 cups (260 grams) all-purpose flour
1 1/4 cups (250 grams) granulated white sugar
2 teaspoons baking powder
1/2 teaspoon salt
2/3 cup (60 grams) Dutch processed cocoa powder, sifted
1 cup (170 grams) semisweet chocolate chips
 Preheat oven to 350 degrees ). Place rack in the middle of the oven. Line 16 muffin pans with paper liners or spray with a non stick vegetable spray.
In a medium sized bowl, whisk the ricotta cheese and then add the eggs, one at a time, beating well after each addition. Add the milk, vanilla extract, and cooled and melted butter, mixing well. Set aside.
In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and cocoa powder. Add the ricotta mixture to the flour mixture. Stir just until combined and then fold in the chocolate chips. Do not over mix this batter or the muffins will be tough when baked.  
Divide the batter amongst the 16 muffin cups using two spoons or an ice cream scoop.
Place in the oven and bake about 20 minutes or until lightly browned and a toothpick inserted in the center of a muffin comes out clean. Remove from oven and place on a wire rack to cool.