Oat Squares with Chocolate Condensed Milk Filling

Introduction

These oat squares use a crumbly brown sugar and rolled oat base, then layer in a filling of sweetened condensed milk and melted chocolate chips. You bake them for 20 to 25 minutes, just until the top turns light golden and the center finishes setting as it cools. They work well as a cut-and-serve dessert bar, lunchbox bake, or make-ahead treat.

Recipe Details

• Prep Time: 20 minutes
• Cook Time: 30 minutes
• Total Time: 50 minutes
• Servings: 16 squares

Ingredients

Base and topping

• ½ cup (120 g) margarine, softened
• 1 cup (240 g) brown sugar
• 1 egg
• 1 teaspoon vanilla
• 1 ¼ cup (300 g) all-purpose flour
• 1 ½ cup (350 g) rolled oats
• ½ teaspoon baking soda
• ½ teaspoon salt

Filling

• ⅔ cup (160 ml) sweetened condensed milk
• 1 cup (240 g) chocolate chips
• 2 tablespoons hard margarine
• 1 teaspoon vanilla
• ¼ teaspoon salt

Instructions

Base and topping

1. Cream together the margarine and brown sugar until light and fluffy.
2. Beat in egg and vanilla.
3. In a mixing bowl, blend together the flour, oats, baking soda and salt.
4. Mix flour mixture into creamed mixture, using a wooden spoon to start, until crumbly looking.
5. Reserve roughly ⅓ of the mixture in a bowl and set aside.
6. Press remaining mixture into a greased, lined square pan.

Filling

1. In a mixing bowl over a pot of boiling water, heat all filling ingredients until chocolate chips are just melted.
2. Spread chocolate mixture evenly over prepared base, keeping the sides of the pan clean.
3. Take reserved mixture and sprinkle over the top. Note that it will not cover the whole surface.
4. Bake at 350°F (180°C) for 20 to 25 minutes, or just until oatmeal mixture has a light golden colour.
5. Let cool, cut, and serve.

Variations

• Use dark chocolate chips instead of regular chocolate chips if you want a less sweet filling and a slightly firmer set once cooled.
• Swap light brown sugar for dark brown sugar to give the base a deeper molasses flavor and a softer chew.
• Replace up to ½ cup of the rolled oats with quick oats if needed; the topping will be finer and less textured.
• Replace the egg with 1 tablespoon ground flaxseed mixed with 3 tablespoons water for an egg-free version; the base will hold together but bake up a bit more tender and crumbly.
• Stir ½ cup chopped walnuts into the reserved topping mixture before sprinkling it over the filling for added crunch.

Tips for Success

• Cream the margarine and brown sugar until the mixture looks lighter and fluffier, not just combined, so the base bakes up less dense.
• Stop mixing once the flour mixture is incorporated and the dough looks crumbly; overworking it can make the pressed base tough.
• Heat the filling only until the chocolate chips are just melted, since overheating can make it thicker and harder to spread evenly.
• Keep the sides of the pan clean when you spread the filling so exposed chocolate does not catch and harden at the edges.
• Let the bars cool completely before cutting, otherwise the filling will smear and the squares will not hold clean edges.

Storage and Reheating

Store the cooled squares in an airtight container with parchment between layers in the fridge for up to 5 days. For longer storage, wrap the squares individually or separate layers with parchment, then freeze in a sealed freezer container or bag for up to 2 months.

These are better brought back to room temperature than fully reheated. Let chilled squares sit out for 15 to 20 minutes before serving, or warm one square in the microwave for 8 to 10 seconds if you want the filling slightly softer. Thaw frozen squares in the fridge overnight.

FAQ

What size square pan should you use?

An 8-inch square pan gives you thicker bars. A 9-inch square pan also works, but the bars will be thinner and may bake a few minutes faster.

Can you use quick oats instead of rolled oats?

Yes. The bars will still hold together, but the topping and base will have a finer, less chewy texture.

Why doesn’t the oat topping cover the whole surface?

That is expected for this recipe. The gaps let some of the chocolate filling show through and help the top stay crumbly instead of forming a solid lid.

Can you make these without the egg?

Yes, you can use a flax egg made from 1 tablespoon ground flaxseed and 3 tablespoons water. The bars will be slightly more delicate, so let them cool fully before slicing.