Gather the muffin ingredients - * Butter * Vegetable oil * Milk * Eggs * Vanilla extract * Flour * Baking powder * Peaches
In a large bowl, whisk together the granulated sugar, melted butter, and vegetable oil.
Next, whisk in the milk, eggs, and vanilla.
Whisk in the flour and baking powder.
When the flour is almost fully incorporated, add the peaches and gently fold them into the batter.
Gather the streusel ingredients - * Brown sugar * Flour * Butter
In a small bowl, mix together the flour, brown sugar, and melted butter until the mixture resembles wet sand. Set aside until ready to use.
Divide the batter between the muffin pans, filling each one completely full.
Top the muffins with the streusel (below).
Bake at 425 degrees F for 5 minutes. Then reduce the oven temperature to 350 degrees F and bake for an additional 15 minutes.
Remove the muffins to a wire rack and allow them to cool completely before storing. Store any leftovers in an airtight container at room temperature for up to three days.