Grease a 12 cup Texas-sized muffin pan or line with paper liners.
In a medium mixing bowl, sift together flour, baking powder, baking soda and salt. In a large mixing bowl, whisk together oil, egg, sugar and vanilla. Whisk in flour mixture, alternating with milk, until just combined. Stir in blueberries and peaches until combined. Divide batter into muffin cups.
To make the streusel, in a large bowl, combine butter, flour, brown sugar, almonds and cinnamon. Beat together, using a mixer on low speed until incorporated and crumbly. Sprinkle streusel on top of muffin batter. Chill muffins in refrigerator for 1 hour.
Heat oven to 350 degrees F. Bake muffins 25-30 minutes or until golden brown and well risen. Cool 10 minutes before transferring to a wire rack.