Preheat oven to 375F and prepare a 9x13 casserole dish with parchment paper.
Toss pecans (1 cup), almonds (1 cup), walnuts (2 cups) and coconut (1 cup) in a food processor, and pulse 3-5 times using 1-second intervals. (You want your nuts to be able the size of a piece of oatmeal, too small and you'll miss out on the texture!)
Spread nuts/coconut in an even layer on a rimmed baking sheet and toast until golden brown (about 7-9 minutes).
Meanwhile, melt the butter (1/2 cup) in the microwave in a large bowl and allow it to cool slightly.
Stir in the erythritol (1/2 cup), ground flaxseed (1 cup), and salt (2 teaspoon).
Stir in the eggs (2) and egg whites (2).
Once toasted (and cooled!), toss in the nuts and sugar free chocolate chips (1 cup).
Line a 9x13 baking dish with parchment paper.
Press the granola bar into the baking dish. Smooth out the top with a rubber spatula.
Bake in preheated oven for 33-36 minutes, rotating the casserole dish halfway in between. You'll know they're done once the center is set, and the edges begin to brown.
Cool bars completely in the pan.
Once cooled, remove the parchment, slice, and enjoy!