Preheat the oven to 350°F and line a baking sheet with parchment paper. Cut the peppers in half lengthways. Scoop out the seeds and arrange the peppers on the baking sheet.
In a bowl mix the Boursin cheese with the garlic, half the gruyere, and the green onion.
Use a teaspoon to scoop the cream cheese mix and fill the peppers.
Sprinkle the rest of the shredded gruyere over the peppers. Bake in the oven for 15 minutes or until the cheese is bubbly and golden brown.