(170 mL)frozen blueberries, reduced over heat to 1/3 cup (75 mL)
(0.5 mL)cream of tartar
Additional butter and sugar for dishes
Preheat oven to 375° F (190°C).
Use additional butter and sugar to grease and line eight 4-inch (10 cm) diameter ramekins.
In a medium saucepan, melt butter over low heat. Stir in flour and salt, and cook for 1 minute. Whisk in milk all at once. Continue whisking until mixture boils and is smooth and thickened.
In a bowl, beat yolks well and add 1/4 cup (60 mL) of the warm sauce mixture to them. Combine yolk mixture with remaining sauce, blending thoroughly. Add cooled blueberry reduction. Set sauce aside to cool slightly.
In a large bowl, using clean beaters, beat egg whites and cream of tartar until soft peaks form; continue beating, gradually adding sugar until stiff peaks form. Fold about a quarter of the egg whites into the sauce to make it lighter, then gently, but thoroughly fold the sauce into the remaining egg whites.
Carefully spoon about 3/4 cup (175 mL) of mixture into prepared ramekins. Bake 20 to 25 minutes or until done. Serve immediately.