01 - Preheat the oven to 375°F. Line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - In a large bowl, whisk together flour, baking powder, baking soda, and salt until well combined. Set aside.
03 - In a separate bowl, mix vegetable oil and granulated sugar until blended. Beat in eggs one at a time, then add milk and vanilla extract.
04 - Pour the wet mixture into the dry ingredients. Stir gently until just combined, being careful not to overmix. Fold in chopped strawberries.
05 - In another bowl, blend cream cheese, granulated sugar, egg yolk, and vanilla extract until smooth and creamy.
06 - Spoon approximately 2 tablespoons of muffin batter into each prepared muffin cup. Add 1 tablespoon of cream cheese filling on top, then cover with another tablespoon of batter.
07 - Gently swirl with a toothpick to create a marbled pattern, if desired.
08 - Bake for 20 to 22 minutes until muffins are lightly golden and a toothpick inserted comes out clean, avoiding the cream cheese center.
09 - Let muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely before serving.