Caramel Apple Bars with Crumbly Oatmeal Streusel

"Nate and the boys and I keep finding ourselves at holiday parties all over the place – tis the season – and we're noticing an interesting trend this year. People aren't hosting big sit-down things like they used to, opting instead for small plates and cookie potlucks. We don't always have time to eat on our own before we head to a party, so I've been trying to come up with extra-hearty recipes to bring along. These caramel apple bars are just the ticket!"