Cheesy Chickpea Salad Toast

Name: Cheesy Chickpea Salad Toast
Ingredients: 6 Tbsp. unsalted butter, room temperature; 2 Tbsp. extra-virgin olive oil, plus more for drizzling; 8 thick slices sourdough or French bread; 2 15-oz. cans chickpeas, rinsed; ½ small red onion, finely chopped; 2 celery stalks, finely chopped; 8 oz. extra sharp cheddar, coarsely grated; ½ cup coarsely chopped cornichons; ½ cup coarsely chopped dill; Kosher salt, freshly ground pepper; Flaky sea salt; Hot sauce and potato chips (optional; for serving)