HEAT oven to 225°F. BEAT egg whites and cream of tartar in mixer bowl with whisk attachment on high speed until foamy. BEATING constantly, ADD sugar, 2 Tbsp. at a time, until whites are glossy and stand in stiff peaks.
FOLD IN ground almonds. SPOON into pastry bag fitted with large fluted or plain tip. PIPE meringue onto baking sheets lined with parchment paper or aluminum foil. Sprinkle with sliced almonds.
BAKE in 225°F oven until firm, about 1 hour. TURN OFF oven. LET DRY in oven, with door closed, until cool and crisp, at least 1 hour.
- 1 cup granulated sugar can be substituted for the powdered sugar. Beat after each addition until sugar is dissolved before adding the next. Rub a bit of meringue between thumb and forefinger; it should feel completely smooth.
- To store: Place meringue kisses in tightly sealed container, with waxed paper between layers.
- For more detailed meringue techniques and information, see Basic Hard Meringue.