Preheat the oven to 220°C (425°F) and line a 12-count muffin tin with paper liners or spray with baking spray.
In a medium mixing bowl, whisk together flour, baking powder, salt, and cinnamon. Set aside.
In a large mixing bowl, whisk together vegetable oil and brown sugar until combined.
Add eggs to the wet ingredients and whisk until smooth. Then, add sour cream and vanilla, and whisk until smooth.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Stir in milk until well incorporated, then fold in chopped peaches.
Divide the batter evenly among the muffin sections.
In a medium-sized bowl, stir together sugar and melted butter until combined. Add flour and salt, mixing until crumbly.
Sprinkle streusel evenly over each muffin.
Bake at 220°C (425°F) for 5 minutes, then reduce heat to 175°C (350°F) and bake for an additional 16-18 minutes, or until a toothpick inserted into the center comes out mostly clean.
Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool completely. Serve warm or at room temperature.
Enjoy!
