Lemon Blueberry Pavlova

Instructions

• Prepare lemon curd filling: Cut butter into small pieces and set aside.
• Separate eggs, placing yolks in a heat-proof bowl and whites in glass, metal, or ceramic bowl. Cover egg whites and leave on the counter to come to room temperature for the meringue.
• Add lemon zest, salt, sugar, and lemon juice to egg yolks. Whisk until thoroughly combined.
• Add 1 to 2 inches water to a saucepan over low heat; bring to a simmer. Place bowl of filling over the simmering water. Cook, stirring constantly with a spatula, until mixture is very hot to the touch and thick enough to coat the back of a spoon, 10 to 15 minutes.
• Stir in butter, 3 or 4 pieces at a time, waiting until butter has melted before each addition. Remove from the heat and pour filling into a bowl to cool, about 15 minutes. Lay plastic wrap on top of the filling, pressing down so it doesn't develop a skin, and place in the refrigerator until well chilled, 2 to 3 hours.
• Preheat the oven to 250 degrees F (120 degrees C). Line a baking sheet with a silicone liner, such as Silpat®. Lightly spray with cooking spray.
• Begin meringue: Mix cornstarch into sugar and set aside.
• Add cream of tartar, lemon juice, and vanilla to the reserved egg whites. Whisk with a large whisk until very soft peaks form, about 3 minutes. Whisk in sugar mixture, 2 tablespoons at a time, whisking about 1 minute between each addition, until incorporated. When all sugar mixture has been added, continue to whisk until relatively stiff peaks form and whites are firm enough to hold their shape.
• Use 2 spoons or a piping bag to transfer whites onto the prepared baking sheet, forming a ring of dollops about 8 or 9 inches across. Fill in the middle with meringue, then go back around the edges adding more meringue to build up the outside edge.
• Bake in the center of the preheated oven for exactly 1 hour. At 1 hour, turn off the oven and crack the door. Let meringue sit in the oven until its cooled completely, about 1 hour.
• Meanwhile, prepare blueberry sauce: combine 1 cup blueberries, sugar, and water in a saucepan over medium heat; bring to a simmer. Cook, stirring occasionally, until blueberries collapse and liquid thickens, about 10 minutes.
• Remove from the heat and pass through a fine mesh strainer. Place in the refrigerator until fully chilled, about 45 minutes.
• Very carefully transfer cooled meringue to a serving platter using 2 large spatulas if necessary; you may get some cracks but that's okay. Use a spoon to crack the center a bit to make room for the filling.
• Fill the center with chilled lemon curd filling. Place remaining blueberries over top and drizzle with blueberry sauce. Garnish with mint.