Bring a large pot of water to a boil (the cauliflower should fit to float upside down in it)
Remove the leaves and cut away the bottom core of the cauliflower (important to make it flat so it can stand on its own in the oven)
Add the remaining ingredients to the pot and place the cauliflower with the core facing up and boil for around 15 min then drain it.
Prepare cauliflower for the oven
Place the cauliflower in an oven form that fits rather snugly around (we want just enough room for pouring in the tomatoes later on)
Mince garlic and mix with smoked paprika, thyme and oil. Brush it evenly all over the cauliflower then squeeze the remaining ½ of the lemon over it
Bake for 30 min then add the crushed tomatoes in the oven form and bake another 10 min
Feta cheese sauce
While the cauliflower is in the oven you can prepare the feta sauce. Start by melting the butter in a saucepan then whisk in the flour and let it heat up another minute while stirring
To save some time I usually heat up the milk and cream in the microwave before adding it to the pan. Add salt and rosemary, whisk until smooth and bring to a boil, then turn down the heat and let it simmer for 10 min.
Add the feta cheese in crumbles and whisk until melted. Cook until melted then finish with a pinch of nutmeg.
Serve the cauliflower hot and pour over feta cheese sauce!