Step 1

Preheat oven to 180C. Cook pasta in a large saucepan of boiling salted water until al dente, adding cauliflower in the last 3 minutes of cooking (6-8 minutes). Drain and return both to pan. Add cream, then cheeses and herbs, season generously to taste and mix well. Spread in a 3-litre baking dish, scatter with extra cheddar and bake until golden and bubbling (10-15 minutes).

Step 2

For crunchy rye crumbs, melt butter and oil in a frying pan over medium-high heat until foaming, add crumbs and stir occasionally until crisp and golden brown (4-5 minutes). Add garlic, thyme and lemon rind and stir until fragrant (1 minute). Remove from heat and season to taste. Scatter over hot macaroni and serve.