Preheat the oven to Gas Mark 4, 180°C, fan 160°C. Butter 4 x 150ml (¼pt) ramekins with softened butter and set aside.
Melt the butter in a pan. Stir in the flour to make a smooth paste and cook for 2 mins. Whisk in the milk. Bring to the boil and cook for 4 minutes until thickened.
Remove from the heat, add the goat’s cheese, mustard, lemon thyme leaves and egg yolks. Beat well and season.
Whisk the egg whites with an electric hand whisk until stiff. Mix a spoonful into the cheese mixture, then gently fold in the rest with a spoon. Fill the ramekins to the rim and place in a baking tray filled with boiling water. Bake for 15-20 minutes, remove, cool and chill.
Preheat the oven to Gas 7, 220°C, fan 200°C. Turn out the soufflés into a dish. Drizzle with cream, scatter with pecorino and bake for 10 minutes. Scatter over sunblush tomatoes and thyme, and serve with rocket drizzled with oil and vinegar.