Melt 2 tablespoons butter in a heavy saucepan over low heat; whisk in flour until smooth. Cook 1 minute, whisking constantly. Stir in green onions and next 3 ingredients; cook 2 to 3 minutes, whisking constantly. Gradually whisk in milk; cook over medium heat, whisking constantly, until mixture is thickened and bubbly.
Combine egg, crabmeat, and cracker crumbs; toss gently. Stir in milk mixture. Shape into 6 patties (or chops).
Combine breadcrumbs and Rustic Rub in a shallow dish. Dredge patties in crumb mixture. Cover and chill 1 1/2 hours.
Cook crab cakes in 1/4 cup melted butter and hot oil in a large skillet over medium-high heat 3 to 4 minutes on each side or until golden. Garnish, if desired.