For Cookies (if making homemade): Grind oats in a food processor or blender until fine. Combine the ground oats with the flour, baking soda, salt and cinnamon in a medium bowl. Cream together the butter, sugars, vanilla, and lemon juice in another medium bowl with an electric mixer. Add the eggs and mix until smooth. Stir the dry mixture into the wet mixture and blend well. Add the chocolate chips and nuts to the dough and mix by hand until ingredients are well blended.
For Brownies: Make the brownie batter in a medium bowl according to the package directions (Note: you will only need HALF of the 18-oz box and ingredients called for on the box - the remaining batter can make extra brownies or cupcakes). To make homemade batter, beat the butter and sugar in a medium bowl until fluffy. Then beat in the vanilla and eggs one-by-one. Stir in the flour and cocoa until combined.
Preheat the oven to 350°F (177°C). Line an 8-inch square baking pan with parchment paper and set aside.
Press the cookie dough into the bottom of the pan using your fingertips. You want an even layer.
Arrange the caramels in a single layer of 4x4 on top of the cookie dough. It's fine if there's some wiggle room between the caramels.
Pour the brownie batter evenly across the caramels (it should be just enough to thinly cover the caramels.) Use a spatula to spread it out to fill the nooks and crannies as needed.
Bake for 35-40 minutes or until a toothpick or cake tester inserted in the middle comes out clean.
Remove from the oven and allow the brownies to cool completely in the pan for at least one hour. This is crucial to prevent the layers from deflating or collapsing.
Use the parchment to lift the brownies out of the pan. Use a sharp knife to cut into squares. Serve with extra Milk Chocolate Caramels, chopped, or ice cream if desired!