Start by preheating the oven to 350 degrees F. Line an 8×8 metal pan with parchment paper.

In a large bowl (or a stand mixer), combine melted butter, brown sugar, and sugar. Whisk or mix until well combined.

Then, add your egg and whisk until incorporated and smooth. Add vanilla and stir to mix it in.

Add gluten-free flour, salt, and baking soda. Add the gluten-free oats and stir until just combined. The dough will be wet and sticky at this point. Don’t panic!

For the top layer. (You’ll use this to dollop dough for the top layer in a minute.)

Out into your prepared pan in an even layer. Again, it’ll be sticky, so go slow or use parchment paper to help you pat it out into an even layer. Set this aside for a minute.

Combine chocolate chips, sweetened condensed milk, and 2 Tablespoons butter (and a pinch of salt if you’re using unsalted butter!) in a small saucepan. Whisk or stir over low heat, stirring constantly, until the fudge mixture is smooth and glossy. (You don’t want it to simmer or boil, so be sure to keep the heat low!)

Then, pour your fudge filling over the oatmeal cookie crust and spread out into an even layer. (It should mostly spread out for you, you may just need to coax it into the corners).

Now, take small blobs of your remaining dough and add them to the top of the fudge layer. You will NOT have enough to cover the top in an even layer–instead it’ll just be dollops of dough. Try to spread out the dough fairly evenly for best results.

Now you’re ready to bake! Bake the oatmeal fudge bars for 25-28 minutes, or until the filling is bubbling around the edges and the dollops of cookie dough on the top look just golden brown.

This will take about 3 hours! Don’t rush it or your fudge filling won’t be as set. If you need to speed things up, you can place the pan in the refrigerator.

At room temperature 2-3 days, the refrigerator 3-4 days, or the freezer up to 6 weeks.