01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - Whisk together flour, baking powder, baking soda, and salt in a large bowl until evenly combined.
03 - Mix vegetable oil and granulated sugar in a separate bowl until blended. Beat in eggs one at a time, then add milk and vanilla extract.
04 - Pour wet ingredients into dry ingredients and stir gently until just moistened. Avoid overmixing to ensure tender texture.
05 - Gently fold chopped strawberries into the batter until evenly distributed.
06 - Blend softened cream cheese, granulated sugar, egg yolk, and vanilla extract in a bowl until completely smooth and creamy.
07 - Spoon approximately 2 tablespoons of muffin batter into each prepared muffin cup, spreading evenly across the bottom.
08 - Place 1 tablespoon of cream cheese filling in the center of each cup on top of the batter layer.
09 - Top each cup with another tablespoon of batter, covering the cream cheese filling completely.
10 - Gently swirl a toothpick through the batter and filling once to create a marbled pattern, if desired.
11 - Bake for 20 to 22 minutes until lightly golden and a wooden pick inserted into the muffin portion comes out clean. Avoid testing the cream cheese center.
12 - Let muffins cool in the tin for 5 minutes before transferring to a wire rack to cool completely.