In a medium bowl, sift together 1 ½ 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 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 ½ 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 preheated oven at 325F for about 20-30 minutes or until 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.