1. 1. Preheat oven to 400°F (200°C). Line a 12-cup muffin tin with paper liners or grease well.

2. 2. Prepare cream cheese swirl: In a small bowl, beat cream cheese, 1/4 cup sugar, egg yolk, and 1/2 tsp vanilla until smooth. Set aside.

3. 3. In a large bowl, whisk flour, 3/4 cup sugar, baking powder, baking soda, and salt. Make a well in the center.

4. 4. In a separate medium bowl, whisk egg slightly. Add milk, oil, lemon juice, lemon zest, and 1 tsp vanilla. Whisk until combined.

5. 5. Pour wet ingredients into dry well. Gently fold with a spatula until just combined (do not overmix; lumps are fine).

6. 6. Divide about two-thirds of the batter evenly among the muffin cups. Spoon about 1 tablespoon of cream cheese mixture on top of each. Top with remaining batter, filling cups nearly full. Use a toothpick to gently swirl the cream cheese into the batter.

7. 7. Bake at 400°F for 5 minutes, then reduce oven temperature to 375°F (190°C) without opening the door. Continue baking for 15–18 minutes or until golden and a toothpick inserted into muffin (avoiding cream cheese) comes out clean.

8. 8. Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.