Step 1

Preheat the oven to 350 degrees F and line an 8×8-inch baking pan with parchment paper, leaving a few inches overhang on two sides so you can easily lift the bars out when they're cooled.

Step 2

To a medium bowl, add the oats, flour, sugar, melted butter, milk, vanilla, and salt. Stir well to combine into a uniform mixture. It will be thick and it should hold together easily when pressed between your fingers.

Step 3

Set aside 1 cup of the batter to use as the topping.

Step 4

Add the remaining batter mixture to the bottom of the prepared pan, pressing evenly to cover completely.

Step 5

Evenly spread the blueberry jam over the batter. Then, sprinkle on the blueberries and lemon zest. Press the berries down very slightly.

Step 6

Crumble the remaining dough mixture over the top to cover evenly and press it down slightly.

Step 7

Bake for 35-40 minutes or until lightly browned. Remove pan from the oven and let cool on a wire rack until room temperature.

Step 8

Use the parchment paper to lift the cooled bars out of the pan. Slice into bars carefully using a serrated knife.