Whisk the flour, baking powder, and salt in a bowl.
In a large bowl, whisk the oil, melted butter, sugar, condensed milk, eggs, lemon zest, and vanilla until smooth.
Sift the flour mixture into the wet ingredients. Mix gently with a spatula until no dry flour remains. Don’t overmix.
Mix in 3 ounces of grated cheese. Save 1 ounce for topping.
Cover and refrigerate for 1 hour or overnight, if you have time. You can also bake right away.
Preheat the oven to 375°F (190°C). Line the muffin pan with cupcake liners or lightly grease the cups.
Divide the batter among the cups, filling almost to the top. Sprinkle with the reserved cheese.
Bake for 5 minutes. Without removing the pan, lower the oven to 350°F (175°C). Bake for another 15 minutes, until a toothpick comes out with a few moist crumbs and no wet batter.
Cool in the pan for a few minutes. Remove the cupcakes and place on a wire rack to cool completely.