01 - Set oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease.
02 - In a large mixing bowl, whisk together flour, granulated sugar, baking powder, baking soda, and salt until evenly blended.
03 - In a separate medium bowl, whisk ricotta cheese, eggs, milk, vegetable oil, and vanilla extract until smooth and fully combined.
04 - Pour the wet mixture over the dry ingredients and gently stir with a rubber spatula just until combined, taking care not to overmix.
05 - Fold in 3/4 cup of the chopped walnuts, reserving the remainder for the topping.
06 - Divide batter evenly into the prepared muffin cups. Sprinkle each with reserved walnuts and demerara sugar.
07 - Bake for 18 to 22 minutes, or until muffins are golden and a toothpick inserted in the center emerges clean.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool fully before serving.