1-First, preheat your oven to 375°F (190°C) and line a muffin tin with paper liners. This step sets the stage for even baking and makes cleanup a breeze. It’s one of those little things that can make your kitchen time more enjoyable.

2-In a large bowl, stir together the vegetable oil and melted butter. This mix adds both moisture and a rich flavor that keeps the muffins tender. Next, add the sugar, egg, and egg white, whisking everything until it’s well combined for a smooth base.

3-Then, whisk in the buttermilk and vanilla extract to bring in that tangy sweetness. In another bowl, whisk together the flour, cornstarch, baking powder, and salt. Gently fold the dry ingredients into the wet ones until mostly combined, being careful not to over-mix this keeps the muffins light and fluffy.

4-Once that’s done, fold in the blueberries until just mixed. Prepare the filling by mixing the softened cream cheese, granulated sugar, and vanilla extract until smooth. For the streusel, whisk together the flour, brown sugar, and salt, then drizzle in the melted butter and toss with a fork until clumpy.

5-Divide the batter into 15 muffin cups, filling each about two-thirds full. Make a small crater in each, add about 2 teaspoons of cream cheese filling, top with more batter, and gently swirl it with a knife. Sprinkle the streusel on top and bake for 25 minutes or until done. Let them cool for about 10 minutes before serving these steps make the process straightforward and fun.