Preheat oven to 350°F. Line a 9x9-inch square baking pan with a parchment paper sling to make it easy to lift the bars out and cut them later after they have cooled completely.
In a large bowl, whisk the butter, brown sugar, and vanilla together.
3/4 cup salted butter, 3/4 cup (150g) light brown sugar, 2 teaspoons vanilla extract
Add the flour, oats, baking soda, and salt, stirring until everything is combined.
1 cup (141g) all-purpose flour, 1 cup (90g) old fashioned oats, 1 teaspoon baking soda, 1/2 teaspoon salt
Press half of the oatmeal dough evenly into the prepared pan. It will be a very thin layer, but don't worry!
Bake for 8-10 minutes until just golden.
While the bottom layer bakes, heat the unwrapped caramels and cream in a small saucepan over medium-low heat, stirring frequently until the caramels are melted and smooth. Remove from the heat.
40 soft caramels, 1/3 cup heavy cream
Sprinkle the chocolate chips over the partially baked bottom layer, then pour the caramel over the chocolate chips. Scatter the remaining oatmeal dough over the caramel by breaking apart small chunks. No need to worry about completely covering the caramel. Gaps are just fine!
1 1/3 cups milk chocolate chips
Bake for another 16-18 minutes, until the edges are golden brown. The middle will continue to set as the bars cool. Remove from the oven and cool completely, at least 2 hours, before cutting into squares. You can slice them sooner, but they won't slice clean and you will have an ooey-gooey (albeit delicious) mess on your hands.