Preheat the oven to 400°F. In a large bowl, combine the flour, sugar, baking powder, and salt.
In a small bowl, beat the egg with the milk and oil. Stir the wet ingredients into the dry ingredients just until moistened. Fold in the chocolate chips and strawberries.
Fill greased or paper-lined muffin cups 3/4-full.
In a separate small bowl, combine the streusel ingredients - cutting the butter into the flour and sugar until it forms coarse crumbs. Sprinkle the streusel mixture evenly over the tops of the muffins.
Bake for 18-20 minutes or until the muffins test clean when a toothpick is inserted near the middle.
Cool 5 minutes before removing to a wire rack to cool completely.
Notes
How long do muffins last?
You'll want to use this recipe within 2-3 days. If you need more time than that, freezing is your best option.
Can muffins be frozen?
Yes! Once the muffins are completely cool, wrap each one individually in plastic wrap or aluminum foil, then place them in a large zip-top bag or freezer-safe container. They'll be good for up to 3 months. When you're ready to eat them, remove the desired number of muffins from the freezer and unwrap them. Allow them to thaw at room temperature.
What is the best way to reheat muffins?
Microwave them on HIGH power for 20-45 seconds or until heated through, depending on your microwave.