Preheat oven to 200°C and grease a muffin tin with butter.
Poach pears with half the sugar and lemon halves in simmering water for 15 minutes.
Melt remaining sugar into a golden caramel then swirl in 25g of butter.
Coat each muffin hole base with caramel and add a thick disc of poached pear.
Cover each pear with a puff pastry disc and bake for 15 minutes until golden.
Rest tartlets for one minute before turning them out onto a serving plate.
Season the grouse inside and out with salt and pepper.
Brown the grouse in 25g of foaming butter in a large frying pan.
Roast grouse with thyme and celeriac in the oven for 20 minutes.
Move meat and vegetables to a warm plate and let the grouse rest.
Deglaze the roasting tray with port and reduce the liquid by half.
Add chicken stock and simmer until reduced by one-third.
Strain the sauce and whisk in half of the remaining butter.
Wilt the kale in a hot pan with butter and a splash of water.
Plate the celeriac, kale, carved grouse, and tartlet then drizzle with port sauce.