Polenta Bake With Plums and Berries (Gluten-Free)

1 3/4 cups plain low-fat yogurt 2 cups low-fat (1%) milk 1 teaspoon fine sea salt 1/2 cup polenta (not quick-cooking) 1/4 cup (1 ounce) unsalted pistachios,[...]

2 plums (240 g) 160 g red fruit jelly (or mixed berries) 2 eggs 50 g butter (plus a bit more for greasing) 70 g sugar 1 1/2 teaspoons cinnamon 100 g vanilla[...]