- 1/2 pound red beets, peeled, cut into 1/2″ pieces
- 2 cups heavy cream
- 1/2 teaspoon kosher salt
- 1 teaspoon unflavored powdered gelatin
- 3 tablespoons honey
- 1/2 teaspoon vanilla extract
- 1 tablespoon finely grated Meyer lemon zest
- 1/2 cup fresh Meyer lemon juice
- 1/2 cup (1 stick) chilled unsalted butter, cut into pieces, divided
- 1/2 cup sugar, divided
- 4 large egg yolks
- 1 large egg
- 1/2 cup chilled heavy cream
- Six 8-ounce glasses or ramekins
- Bring beets, cream, and salt to a simmer over medium heat in a medium saucepan. Cover, reduce heat, and simmer very gently until beets are tender, 25–30 minutes. Let cool slightly.
- Meanwhile, combine gelatin and 2 tablespoons cold water in a blender; let sit 5 minutes for gelatin to soften.
- Transfer beets and their cooking liquid to blender; add honey and vanilla and purée until smooth. Strain through a fine-mesh sieve into a large bowl; discard solids.
- Divide purée among glasses and chill until set, 3 1/2–4 hours.
- Do ahead: Panna cotta can be made 3 days ahead. Cover and keep chilled.
- Bring lemon zest and juice, 1/4 cup butter, and 1/4 cup sugar to a simmer over medium heat in a medium saucepan, stirring to dissolve sugar. Remove from heat.
- Whisk egg yolks, egg, and remaining 1/4 cup sugar in a small bowl until pale and thick, about 2 minutes. Whisking constantly, slowly pour hot lemon mixture into egg mixture. Transfer back to saucepan and cook over medium-low heat, whisking constantly, until curd is thickened and whisk leaves a trail, about 5 minutes. Remove from heat and add remaining 1/4 cup butter, whisking until melted and curd is smooth.
- Transfer curd to a bowl and cover with plastic wrap, pressing directly onto surface. Chill until cold, at least 2 hours.
- When ready to serve, whisk cream in a small bowl to soft peaks and gently fold into curd. Spoon mousse over panna cotta.
- Do ahead: Lemon curd can be made 3 days ahead. Cover and chill.