Preheat oven to 400 degrees and set the oven rack to middle position. Spray a muffin tin with baking spray with flour and set aside.
Place the oats in a large sauté pan over high heat and toast until light golden in color.
Remove from heat and place oats in the bowl of a food processor fitted with the chopping blade. Process oats for about 30 seconds, or until finely ground.
In a lage mixing bowl, combine ground oats, flour, salt, baking powder, baking soda, and cinnamon. Stir to combine.
In another large mixing bowl, combine brown sugar and oil, and stir to break up sugar and dissolve well.
Whisk milk, yogurt, and eggs into the oil/sugar mixture.
Add the dry ingredients into the wet ingredients in two additions, and whisk together until just combined.
Fold shredded cheese and diced apple into the batter
Let the batter sit for about 20 minutes to thicken up.
While the batter is resting, combine remaining streusel ingredient in the bowl of the food processor, and pulse about 10 times until mixture is crumbly.
When batter has thickened, pour about 1 cup into each well of the muffin tin, and spoon about 1 tablespoon of streusel on top.
Bake for 25-30 minutes, or until a toothpick inserted into the middle comes out clean.