Preheat oven to 200c/430f.
Begin by frying your bacon in a pan over medium heat until crispy. Drain away excess fat if necessary (a couple of tsp left in the pan is fine).
Melt in 2 tbsp butter, then stir in 2 tbsp flour until a paste forms. Gradually whisk in your milk 1/2 cup at a time, stirring throughout to ensure no lumps form.
Once thickened, add in 1/4 tsp garlic powder, 1/4 tsp onion powder and 1 tsp dijon mustard. Stir to blend, then add in 1 cup cheddar, 1 cup mozzarella and 1/2 your parmesan. Taste test for salt and pepper.
Meanwhile, pop your gnocchi in salted boiling water and cook for 1-2mins. Do not cook for the full packet instruction time, take at least 1 minute off. It still needs to be fairly firm, this is just to remove the starch and cook through slightly. Drain and combine with your cheese sauce. Pour into an oven safe dish.
Top with other half of parmesan, then 1/2 cup breadcrumbs, followed by a pinch of salt and pepper then spray with oil to finish.
Pop in the oven for 20mins or until golden on the top and bubbling in the centre.