Step 1
Preheat the oven to 450 degrees F (230 degrees C). Generously grease a casserole dish with 1 tablespoon butter. Bring a generously salted pot of water to a rolling boil over high heat.
Step 2
Remove stems from beans by trimming with a knife or snapping them off with your fingers. Cut beans in half.
Step 3
Add beans to the boiling water stir and cook until just barely tender 5 to 6 minutes testing often to make sure you don't overcook them.
Step 4
Remove beans with a strainer and immediately place in a bowl of cold water to stop the cooking process.
Step 5
Once beans have cooled to the touch use your hands to drain and transfer them into the prepared casserole. It's okay if they're still a bit wet.
Step 6
Season beans with pepper kosher salt and Dijon mustard; mix until beans are well coated. Pour in cream scatter Comté cheese over top and sprinkle with Parmigiano-Reggiano.
Step 7
Combine melted butter and bread crumbs in a small bowl. Stir until well combined and mixture resembles wet sand. Spoon and sprinkle bread crumbs over the casserole then dust with cayenne.
Step 8
Bake in the center of the preheated oven until browned and bubbly 15 to 20 minutes.
Step 9
Let cool for 10 minutes before serving.