Heat oven to 375.
In a large bowl, toss the fruit with 1/2 teaspoon the cinnamon and 1 tablespoon of the sugar.
Grease a baking pan: 8 inch square or 9 inch round works well.
In another bowl, stir together remaining cinnamon and sugar and oats and nuts. Add the butter and use clean hands to incorporate into the mixture.
Spread topping over fruit and bake about 40 minutes, until topping is lightly browned and fruit is tender.
Serve hot or cold or in between. Good with ice cream or whipped cream. Very good left over. Can re-heat in microwave if you wish.