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 mixing bowl, whisk together flour, baking powder, baking soda, and salt until well blended. Set aside.
03 - In a separate bowl, combine vegetable oil and granulated sugar, stirring until fully incorporated. Beat in eggs one at a time, then whisk in whole milk and vanilla extract until smooth.
04 - Pour the wet mixture into the dry ingredients. Fold gently with a spatula just until combined, being careful not to overmix. Gently fold in chopped strawberries.
05 - In another bowl, beat softened cream cheese with sugar until smooth and creamy. Add egg yolk and vanilla extract, mixing until fully incorporated and no lumps remain.
06 - Spoon approximately 2 tablespoons of muffin batter into the bottom of each prepared muffin cup. Add 1 tablespoon of cream cheese filling in the center, then top with another tablespoon of batter to cover the filling.
07 - Gently swirl a toothpick through the batter and filling in each cup once to create a marbled pattern, taking care not to over-swirl.
08 - Bake for 20 to 22 minutes until muffins are lightly golden on top and a toothpick inserted into the cake portion (avoiding the cream cheese center) comes out clean.
09 - Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack. Cool completely before serving or storing.