Preheat the oven to 200°C. Line a large tray with baking parchment.
Mix mayonnaise and crushed garlic in a small bowl.
Chop the leaves of parsley and tarragon. In a separate bowl, mix together white breadcrumbs, tarragon, parsley, lemon zest, lemon juice and a pinch of salt.
Place haddock fillets on the baking tray and scatter cherry tomatoes around them.
Spread a layer of garlic mayonnaise on each of the haddock fillets. Then spoon the herby breadcrumb mixture on top and press down so that the breadcrumbs stick to the fish.
Drizzle everything with a little olive oil and pop the tray in the oven to bake for approx. 15 minutes.
Whilst the fish cooks, cook your rice following pack instructions. When cooked, stir in half of the butter.
When your fish and rice are about 3 minutes away from being cooked, melt the rest of the butter in a large frying pan. Add spinach and thinly sliced garlic and stir until all the spinach has just started to wilt - it should only take a couple of minutes.
To plate, use a large spatula (or a dough scraper) to lift the fish out of the baking tray. Serve with spinach, roasted cherry tomatoes and buttery rice on the side.