Preheat oven to 350°F (175°C). Line a large rimmed baking sheet with parchment paper.
Melt butter in a large, oven-safe skillet or saucepan over medium heat. Cook, stirring occasionally, until the butter turns golden brown and smells nutty, about 5-7 minutes.
Whisk in brown sugar and granulated sugar into the browned butter. Cook, stirring constantly, until sugars are dissolved and the mixture is smooth, about 2-3 minutes.
Remove from heat. Stir in vanilla extract and sea salt.
Add flour and oats to the sugar mixture. Stir until just combined and a thick dough forms. Fold in pecans and chocolate chips.
Spread the dough evenly onto the prepared baking sheet. It will be thick.
Bake for 20-25 minutes, or until the edges are deeply golden brown and the center is set.
Let cool on the baking sheet for 5 minutes. While still warm, use a sharp knife or pizza cutter to score the brittle into desired shard shapes.
Let cool completely on the baking sheet until firm. Break apart along the scored lines.
