Step 2 Beat egg whites in medium bowl with electric mixer until frothy. Add cream of tartar and beat until soft peaks form. Gradually beat in sugar, 1 tbsp (15 mL) at a time, until sugar is dissolved and stiff, glossy peaks form.
Step 3 Spread over hot pie filling in decorative swirls.
Step 4 Bake pie in preheated 425°F (220°C) oven until tips of meringue are golden brown, 4 to 5 minutes.