Black Currant and Nectarine Crisp

We had a bunch of black currants given to us that we needed to use up. I didn't like any of the recipes I found, so I made my own. I only put 1/4 cup of sugar in the fruit mix, and it was still very tart. You'll probably need at least 1/2 cup, but maybe more, depending on how tart/sweet you like it.

Filling:
3 cups Black Currants
3 nectarines, diced
zest and juice of 1/2 lemon
1/2 cup granulated sugar
2 Tablespoons plain/all-purpose flour
1/2 tsp vanilla extract

Crisp:
1 1/4 cups rolled oats (I used porridge oats)
1/2 cups plain flour
1/2 cup brown sugar
1/2 tsp. cinnamon
2 ounces butter, diced

Grease a 2 quart casserole dish, and preheat oven to 180 Celsius/350 F. In casserole dish, mix together all ingredients for the filling. In a medium bowl mix together oats, flour, brown sugar, and cinnamon. Then add the butter and rub into the mixture with your fingers until it resembles coarse breadcrumbs. Spread crisp mix evenly over the filling. Bake for 30-40 minutes, or until filling is bubbling and crisp is nicely browned.

Serve warm with custard or ice cream if desired.