In a medium bowl, combine the flour, baking powder, baking soda and salt. Set it aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat together the butter, oil and sugar on medium speed until well mixed. Add the eggs, one at a time, beating well between each addition.
Reduce the mixer speed to low, and then gradually beat in the flour mixture, sour cream and vanilla just until combined.
Layer the batter and streusel in the prepared muffin pan by spooning a portion of the batter, then a sprinkle of streusel, topped by another portion of batter and a final sprinkle of streusel on top.
Bake the muffins until a toothpick inserted comes out clean, 18 to 22 minutes.
Remove the muffins from the oven and let them cool slightly in the muffin pan before transferring them to a rack to cool completely.
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