Gather your equipment and ingredients. I use a small, oven-safe casserole dish, about 8.5 inches by 6 inches. Put a generous pat of butter into the dish and put it into your oven. You want the butter to begin to melt while you prep your other ingredients, so use your judgment as to when to pop it in the oven. You want to take it out when the butter is soft enough to spread easily over the bottom of the pan, but before it burns.
Get your oven, or toaster oven, preheating to 350°F/180°C.
Wash and remove the pits from your stone fruit, then slice thinly. I think I got about 16 slices out of each fruit. Wash your berries.
Is your butter mostly melted? Probably. Carefully remove your casserole dish from the oven and swirl the butter around so it coats the dish completely. Then, pour out the excess butter into a small bowl.
Add the oats, flax seed, chia seeds, salt, and maple syrup to the bowl with the excess butter. Mix thoroughly with a fork.
Spread the sliced stone fruit into your buttered casserole dish. Toss in the handful of berries as well.
Spread the oat mixture on top of the fruit.
Bake in your pre-heated oven for about 30 minutes. It should smell wonderful, be slightly browned, and the fruits should have begun releasing their beautiful juices. Allow to cool slightly, then serve. It's very good with a dollop of plain Greek yogurt. We've been all about the Fage full fat, if you can find it.