How to Make It
Preheat oven to 350°.
To prepare crust, weigh or lightly spoon 5 ounces flour into a dry measuring cup; level with a knife. Combine flour and next 3 ingredients (through baking soda) in a medium bowl. Add 1/4 cup canola oil and 2 tablespoons butter; toss with a fork until crumbly. Remove 3/4 cup of oat mixture; set aside. Press remaining oat mixture into the bottom of an 11 x 7-inch glass or ceramic baking dish coated with baking spray. Bake at 350° for 13 minutes or until lightly browned. Cool slightly.
To prepare filling, weigh or lightly spoon 4 ounces flour into a dry measuring cup; level with a knife. Combine flour and next 5 ingredients (through salt) in a large bowl. Combine milk and espresso granules in a bowl, stirring with a whisk until espresso dissolves. Add 3 tablespoons canola oil, 3 tablespoons butter, vanilla, and eggs to milk mixture, stirring with a whisk. Add milk mixture to flour mixture, stirring to combine. Fold in chocolate.
Spread batter over prepared crust in pan. Sprinkle with reserved 3/4 cup oat mixture. Bake at 350° for 32 minutes or until a wooden pick inserted in center comes out with moist crumbs clinging. Cool in pan on a rack. Cut into 28 bars.