Preheat oven to 350F (175C) and line a 9x9 metal baking pan* with parchment paper -- use enough so that parchment paper hangs over the edges, this will make it easy to lift the bars out of the pan and cut them later on.
Combine your melted butter and vanilla extract and stir until combined. Set aside.
Prepare your dry ingredients by stirring together flour, oats, brown sugar, baking soda, and salt until well-combined.
Add butter and stir until ingredients are combined.
Press half of your oat/butter mixture evenly and firmly into the bottom of your prepared 9x9 pan and transfer to your 350F (175C) oven to bake for 8-10 minutes (until just lightly golden).
Meanwhile, prepare your caramel filling by combining unwrapped caramels and heavy cream in a small saucepan over medium-low heat. Stir frequently until caramel is completely melted and mixture is smooth, then remove from heat.
Once your first layer of the Carmelita is finished baking, remove from the oven and sprinkle evenly with milk chocolate chips.
Pour caramel evenly over chocolate chips, and then scatter remaining oat mixture over the top of the caramel, you don't have to completely cover the caramel, gaps are OK. I like to gently press the oat mixture into the caramel but be careful not to touch the caramel as it's hot!
Return to 350F (175C) oven and bake for another 18-21 minutes or until top is golden brown.
Allow to cool completely, at least 1-2 hours, before removing from the pan and cutting and serving (if you dig in too soon you'll have a major mess on your hands, you need to allow some time for the caramel to re-set).
*This recipe will work in a glass pan instead, but it will likely take longer to bake.