Heat oven to 350°F. Line an 8-inch square pan with parchment, leaving overhang.
Whisk oats, flour, brown sugar, baking soda, and fine salt in a large bowl.
Stir in melted butter and vanilla until the mixture forms moist clumps.
Press about two-thirds of the crumb into the pan. Bake 10 minutes to set.
Melt caramels with cream in a saucepan over low heat, stirring until smooth. Let stand 2 minutes.
Scatter chocolate chips and pecans over the warm crust.
Pour the warm caramel evenly on top. Sprinkle with flaky sea salt.
Crumble the remaining oat mixture over the caramel, leaving some gaps for bubbling.
Bake 18–20 minutes until golden and bubbling. Cool completely, then chill 1 hour for clean slices.