Preheat your oven to 375°F. Place the butter in your baking dish or skillet and put it in the oven to melt while it preheats.
While the dish is heating, combine the eggs, sugar, flour, salt, milk, cream, vanilla, and almond extract in a blender. Blitz for about 10 seconds until smooth. Scrape the sides if needed, then blitz once more. The batter should be thin, the consistency of heavy cream.
Carefully remove the hot dish from the oven. Swirl the melted butter around to coat the bottom and sides. Pour the batter directly into the dish. Arrange the cherries evenly over the top. Don't push them in — they'll sink on their own as it bakes.
Bake for 30-35 minutes. The edges should be deeply golden and pulling away from the pan. The center should jiggle like Jell-O when you gently shake the dish — not slosh like soup. If it still looks wet in the middle, give it five more minutes and check again.
Place the dish on a wire rack and let it cool for at least 15 minutes. The custard continues to set as it rests, and the flavor blooms as it comes down from oven-hot.
Right before serving, dust the top generously with powdered sugar. Serve warm or at room temperature.