01 - Preheat 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 all-purpose flour, baking powder, baking soda, and salt until thoroughly combined.
03 - In a separate bowl, whisk vegetable oil and granulated sugar until blended. Beat in eggs one at a time, then stir in whole milk and vanilla extract.
04 - Pour wet ingredients into dry ingredients and fold gently with a spatula just until combined. The batter should remain slightly lumpy. Fold in chopped strawberries.
05 - Using an electric mixer or whisk, blend softened cream cheese, sugar, egg yolk, and vanilla extract in a small bowl until smooth and creamy.
06 - Spoon approximately 2 tablespoons of muffin batter into each prepared 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 in each cup to create a marbled effect with the cream cheese filling.
08 - Bake for 20-22 minutes until muffins are lightly golden and a toothpick inserted into the cake portion (avoiding the cream cheese center) comes out clean.
09 - Let muffins cool in the tin for 5 minutes before transferring to a wire rack. Cool completely before serving or storing.