Smoked Cheese and Broccoli Tart

Name: Smoked Cheese and Broccoli Tart
Prep time: 30 min
Cook time: 30 min
Total time: 1 h
Cuisine: European, British
Ingredients: Flour for rolling; 250 g (~ 9 oz) shortcrust pastry; ½ Tablespoon oil; ½ Tablespoon butter; 1 medium leek, (sliced); 300 g (~ ⅔ lb / 1 medium head) broccoli, cut into bitesize pieces; 3 cloves garlic, (minced); 2 eggs; 2 Tablespoons sour cream; ½ teaspoon black pepper; ½ teaspoon salt; 100 g smoked cheddar, (grated (~ 1 cup when grated)); 30 g (~ ½ cup) walnut halves, chopped