Prepare stuffing mix according to package directions; cool.
Meanwhile, in a shallow bowl, mix eggs and mustard. Place flour, salt and pepper in another shallow bowl. Dip chicken thighs in flour mixture to coat both sides; shake off excess. Dip in egg mixture, then again in flour mixture, patting to help coating adhere.
In an electric skillet, heat 1/2 in. oil to 375°. Fry chicken thighs, a few at a time, until golden brown and a thermometer reads at least 170°, 2-3 minutes on each side. Drain on paper towels and keep warm.
Preheat waffle maker. In a large bowl, whisk flour, sugar and baking powder. In another bowl, whisk milk, eggs, butter and vanilla until blended. Add to dry ingredients; stir just until moistened. Stir in prepared stuffing.
Bake waffles according to manufacturer’s directions until golden brown. Serve with chicken and syrup.