Preheat the oven to 350 degrees Fahrenheit
Line a muffin tray with liners and set aside.
In a small bowl, combine all ingredients for the streusel and use a fork to blend together. It should look crumbly and be neither dry nor too wet.
If too wet and mushy, add more flour, if too dry, add more oil until its nice and crumbly. Set aside.
In a large mixing bowl, whisk together all wet ingredients until well combined.
Add in all dry ingredients, making sure to spoon and level the flours into the dry measuring cups.
Use a wooden spoon to fold together until a batter forms. It will be on the thicker side, but definitely shouldn't seem dry.
Use a spoon to fill each muffin tray about 3/4 of the way up.
Sprinkle the crumble on top of each muffin.
Bake for 18-22 minutes or until a toothpick comes out clean.
Let cool in the tray for about 15 minutes, then carefully remove each muffin.