Plum and Blackberry Crumble Sundae

1 cup flour
1 cup oats
10 TBS butter
2/3 light brown sugar
1 tsp cinnamon
1/2 tsp salt
1 pint blackberries
1 TBS Granulated Sugar
2 plums -pitted and sliced
2 tsp fresh lemon juice
1 pint vanilla ice cream

heat oven to 350
mix together flour, oats, butter, brown sugar, cinnamon and salt in a medium bowl.
Transfer to a rimmed baking sheet and using your hands, form mixture into large clumps
Freeze until hard (15 minutes)
Bake the crumble until golden brown 20-25 minutes - and let it slightly cool (i like when its hot and melts the fruit and ice cream)
Meanwhile, mash the blackberries and granulated sugar in a medium bowl. Add plums, lemon juice and remaining pinch of salt and mix to combine.
Divide Ice Cream, fruit and juices and crumble among 4 glasses of bowls. Serve immediately.