Berry and Tarragon Pavlova

INGREDIENTS

• 3 large egg whites
• 1/2 cornstarch
• 1/8 cream of tartar
• 1/2 plus 1/3 cup sugar
• 1 fennel seeds, lightly crushed
• 12 fresh strawberries, hulled, halved or quartered if large (about 3 cups)
• 6 fresh raspberries (about 2 cups)
• 1 finely grated lemon zest
• 1 fresh lemon juice
• 3/4 chilled heavy cream
• 3/4 mascarpone
• 2 fresh tarragon leaves