Preheat oven to 350ºF.
Spray an 8"x8" glass pan with non-stick baking spray or lightly butter bottom of pan.
Cut the fruit into bite-sized chunks.
Put the chunks of fruit into the prepared pan and toss with lemon juice.
In a small bowl mix together the brown sugar, flour, cinnamon and nutmeg.
Sprinkle the sugar mixture over the fruit and toss to coat all the fruit pieces.
For the topping, mix together in a medium bowl the oats, flour, brown sugar, baking powder and sea salt.
Add the melted butter and stir until well incorporated.
Layer the topping on the fruit and spread it to evenly cover.
Bake for 35-45 minutes until the fruit is hot and bubbling.