Preheat the oven to 200°C, 400°F, Gas 6 and put in a baking sheet to warm.
Rub the butter into the flour with the salt until you have coarse breadcrumbs. Add water a little at a time using a round-bladed knife to mix until the mixture just comes together. Form into a ball, cover with clingfilm and refrigerate for 20-30 minutes.
Wilt the spinach leaves in a pan with 1 tbsp water. Drain thoroughly, pressing the water out with a wooden spoon. Set aside.
Roll out the pastry and press it gently into a lightly greased or nonstick baking paper lined flan tin. Prick all over with a fork and bake in the oven on the baking sheet for 20 minutes until pale gold.
Melt the butter in a pan and cook the streaky bacon until the fat has rendered and the pieces lightly gold. Set aside.
Beat the eggs into the ricotta, the grate in a little nutmeg and season. Strew the spinach leaves, bacon and smoked salmon evenly in the pastry base then spoon over the ricotta and egg mixture. Bake in the oven for 30 minutes until the top is golden and lightly puffed.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.