Roasted Carrot & Harissa Galette

Name: Roasted Carrot & Harissa Galette
Prep time: 1 h 40 min
Cook time: 1 h 5 min
Total time: 2 h 45 min
Cuisine: British
Ingredients: 110 grams (3¾ ounces, generous ¾ cup) plain (all-purpose) flour, plus extra for dusting; 110 grams (3¾ ounces, generous ¾ cup) wholemeal (whole-wheat) flour; 150 grams (5½ ounces, ⅔ cup) cold unsalted butter, diced; 1/2 teaspoon fine salt; 100 grams (3½ ounces) mature cheddar, grated; 60 to 80 milliliters (2 to 2½ ounces, 4 to 5 tablespoons) ice-cold water; 450 grams (1 pound) heritage (rainbow) carrots; 2 tablespoons harissa paste; 1 tablespoon honey; 1/2 teaspoon flaky sea salt; 2 to 3 sprigs fresh thyme, plus extra to garnish; 150 grams (5½ ounces, ⅔ cup) mascarpone cheese; 1 egg, beaten; Parmesan, for grating