1. Heat oven to 350 degrees F. Line a rimmed baking sheet with greased foil and arrange crackers in an even layer.
2. In a saucepan, make caramel by heating the butter and sugar over medium-high heat, whisking constantly, until sugar dissolved and mixture has thickened, 3 to 5 min. Pour caramel over crackers, using a spatula to spread in an even layer. Bake until caramel is bubbly, 15 min. Remove from oven and sprinkle chocolate chips evenly over the top; let chocolate sit for 5 min, then spread evenly over crackers. Sprinkle surface with coconut, sesame seeds or crushed peppermint and chill to set chocolate.
3. Transfer to a cutting board and peel away foil before cutting into strips. Store in an airtight container for up to 1 week.