50 gmbutter, coarsely chopped2 tbspextra-virgin olive oil1garlic clove, finely chopped3 tspthyme leaves, plus extra to serveFinelygrated rind and juice of 1 lemon400 gmSwiss brown mushrooms, halved8thick slices of rye bread350 gmGruyère, thinly slicedTo serve:oregano
Preheat oven to 220C. Heat butter, oil, garlic, thyme and lemon rind in a small saucepan over low-medium heat until fragrant (1 minute), season to taste and set aside.
Spread mushrooms on an oven tray, drizzle with half the butter mixture, season to taste and roast until tender and browned (15-20 minutes).
Meanwhile, preheat grill to high heat. Toast bread for 1-2 minutes, turn, arrange Gruyère on top of bread and grill until bubbling (1-2 minutes).
Top Gruyère toast with mushrooms, spoon remaining butter mixture over to taste, scatter with oregano and extra thyme, squeeze lemon juice over to taste and serve.