In a small bowl, combine flour, sugar, brown sugar, salt, and nutmeg; set aside.
Preheat a large skillet over medium-high heat. Add hazelnut pieces, and toast, stirring constantly, until they begin to turn golden and release their fragrance.
Add butter to hot pan and stir with hazelnuts until butter has melted completely. Add flour mixture and cook, stirring constantly, until clumps begin to form and caramelize, about 3 - 4 minutes. Remove from heat and let cool.
Place marionberries in a small saucepan and add honey and lemon zest. Heat over medium heat until the berries begin to release their juices and the honey melts and incorporates evenly into the dish. Remove from heat and keep warm.
Bring 3 cups water and 1/4 tsp salt to a boil then add 1 cup Bob's Red Mill Steel Cut Oats.
Reduce heat to a low simmer. Cover and cook 10 - 20 minutes (depending on how chewy you like your cereal). Stir occasionally.
Remove from heat and let stand covered for a couple of minutes.
Divide oats into serving dishes and top with stewed marionberries. Garnish each dish with a generous amount of hazelnut crumble.