Preheat oven to 350 degrees. In the bowl of a stand mixer, combine flour, sugar, baking powder and salt. With the mixer running on low speed, slowly add eggs, oil, vanilla and orange juice. Mix until combined. Dump dough out onto a well-floured surface, form into a disc, wrap tightly and refrigerate for at least 30 minutes.
Meanwhile - Peel, core and cut apples into cubes. Combine with cinnamon-sugar mixture in a large bowl and let soak.
In a small bowl, combine all streusel ingredients except for butter and whisk to combine. Using a fork, pastry blender or your fingers, work in the butter cubes until the mixture is crumbly.
After dough has chilled, unwrap and place on well-floured surface. Roll out to about 1/4 inch thickness and cut circles approximately 7 inches in diameter (I use a cereal bowl as a stencil). Spray muffin pans with nonstick cooking spray and sprinkle flour in each opening. Place dough rounds in each opening and press the bottom and sides down gently. Let some dough hang over and trim the rest. Don't worry about making it pretty, it's supposed to be rustic! Fill each mini pie with apples and sprinkle streusel on top.
Bake 45-60 minutes, until crust is golden.