In a medium bowl, sift together 1 1/2 cups flour, the granulated sugar, baking powder, and salt; set aside.
In a second bowl, whisk together the egg, milk, canola oil, and vanilla.
Using a rubber spatula, fold dry ingredients into the egg mixture.
Spray each mason jar with cooking oil.
Pour batter into each jar only filling half way.
In a medium bowl, combine remaining 2 1/2 cups flour, brown sugar, and cinnamon.
Pour melted butter over flour mixture, and toss with a rubber spatula until large crumbs form.
Top each jar with crumb topping.
Place all jars on a cookie sheet.
Bake in a preheated oven at 325 for about 20-30 minutes or until a knife comes out clean.
Allow to cool the jars will be very hot.
The cakes stay fresh with the lid for up to 1 week. You can also freeze them.