Flax Seed Burfi (Healthy Nut Bar)

Ingredients:

1/2 cup golden flax seed powder or meal
1/2 cup coarsely ground walnut
1/2 cup coarsely ground almonds
1/2 cup coarsely ground cashews
1 teaspoon crushed cardamom about 8 cardamoms
1 cup sugar
1/4 cup water