Rinse and finely grate the carrots. Separate the eggs. Beat the egg yolks with sugar and lemon zest until frothy. Mix the flour, baking powder and cornstarch. Stir into the egg mixture. Add the carrots and nuts. Beat the egg whites until stiff. Fold into the egg yolk and carrot nut mixture.
Preheat the oven to 160°C (approximately 325°F). Grease the ovenproof glasses with butter and sprinkle with breadcrumbs.
Pour the mixture into the glasses (about 2/3 full). Bake for about 25 minutes until golden brown. Cool and serve dusted with powdered sugar.