01 - Preheat oven to 250°F and line a baking tray with parchment paper. In a clean bowl, whisk egg whites until soft peaks form. Gradually add sugar, whisking until stiff, glossy peaks develop, then beat in vanilla extract. Spoon or pipe small mounds of meringue onto the prepared tray.
02 - Bake meringues for 1 hour, then turn off the oven and allow them to cool completely inside.
03 - Combine frozen mixed berries, sugar, lemon juice, and orange zest in a saucepan. Simmer gently for 5 to 7 minutes until the berries soften and the mixture becomes syrupy. Remove from heat and allow to cool completely.
04 - In a chilled bowl, whip heavy cream with powdered sugar and vanilla extract until soft peaks form.
05 - Roughly crush cooled meringues. In serving glasses or a large bowl, layer meringue pieces, whipped cream, and berry compote. Repeat layers as desired.
06 - Top with extra berries and fresh mint leaves if desired. Lightly dust with powdered sugar before serving.