Equipment Needed
- 9×13 inch baking pan
- Parchment paper
- Two mixing bowls (one large, one medium)
- Whisk and spatula
- Peeler and sharp knife
- Measuring cups and spoons
Step-by-Step Instructions
First, I preheat my oven to 350°F (175°C) and line my 9×13 pan with parchment paper, leaving an overhang on the sides. This “sling” is my best baking hack—it lets me lift the entire batch of bars out for perfect, clean cuts. In my large bowl, I whisk together the flour, oats, brown sugar, cinnamon, baking soda, and salt for the crust. The smell is already heavenly. I then pour in the melted, slightly cooled butter. Using a spatula, I stir until every dry ingredient is moistened and the mixture forms clumps. It will look and feel like wet sand.
Now, I set aside about 1 ½ cups of this crumbly mixture for the topping—I just scoop it into a smaller bowl. I press the remaining mixture firmly and evenly into the bottom of my prepared pan. I really lean into this step, using the bottom of a measuring cup to compact it. A firm, well-pressed base is the foundation that prevents the filling from making it soggy. I pop this crust into the preheated oven for 15 minutes to par-bake. This gives it a head start and ensures it stays crisp under the juicy apples.
While the crust bakes, I make the filling. In my medium bowl, I toss the diced apples with lemon juice (this keeps them from browning), then add the flour, sugar, cinnamon, and vanilla. I stir until every piece is coated. The flour is crucial—it thickens the apple juices as they bake, creating a luscious, sliceable filling instead of a watery mess. When the crust comes out, it will be pale and puffed slightly. I immediately spoon the apple mixture over the hot crust and spread it into an even layer.(See the next page below to continue…)