Preheat oven to 180C/350F.

Mix Topping ingredients in a bowl with a pinch of salt and pepper. Set aside.

Melt butter in a large pot over medium heat. Add garlic and cook for 1 minute until it smells incredible.

Add flour and cook for 1 minute, stirring constantly.

While whisking, slowly pour in half the milk. Once fully incorporated, whisk in the remaining milk plus the chicken broth.

Cook for 4 to 5 minutes, whisking every now and then and more towards the end, until the sauce thickens so that it coats the back of a wooden spoon and when you draw your finger across it, the path stays (see video).

Turn off heat, add cheeses, stir in (don't worry if it doesn't melt fully). Then do a taste test and add a bit of salt if required.

Add broccoli and stir well to coat.

Pour into a casserole dish, pat down to fill. Sprinkle over Topping, cover with foil then bake for 25 minutes.

Remove foil and bake for a further 20 minutes until the topping is deep golden and the broccoli is tender.

Stand for 5 minutes before serving.