Preheat the oven to 350 degrees Fahrenheit.
Combine the softened butter, flour and sugar in a bowl. Mix in both kinds of oats, then the almonds, salt and cinnamon until well combined. I like to mix with my hands. Set aside.
Slice the peaches and add to a large bowl. Toss with all ingredients aside from the tapioca until well combined.
Toss in the tapioca.
Transfer to a large cast iron skillet or baking dish and spread evenly.
Add the crumble on top.
Bake for 40 minutes, then cover with foil and bake an additional 5-10 minutes or until the peaches are a bit bubbly and the top is golden brown. If you notice the top browning too much before the 40 minute mark, you can cover with foil earlier.
Remove from the oven and let cool, then serve with vanilla ice cream or whipped cream and enjoy!