If using boneless chicken thighs, mold them into shape of whole thigh and skewer them to hold together..
Mix 1 tsp salt, 1 tsp garlic powder and 1/8 tsp paprika. Season both sides of chicken and either smoke or grill meat. I smoked them at 250 degrees for an hour and they were perfect.
Melt 1 Tablespoon of butter in small saucepan and saute chopped onions until just starting to turn brown.
In the meantime, boil the potatoes until fork tender, about 15 minutes. Remove from heat, drain off water and return to pan. Do not peel!
Mash potatoes coarsely and add caramelized onions, 1/2 cup of milk, 3 Tbsp of butter and 1/2 tsp of salt and mix thoroughly but gently until combined. Keep warm.
In saucepan, melt remaining 2 Tbsp of butter. Add flour and cook until butter and flour mixture just starts to turn brown.
Add 1/2 cup each of milk and beer to flour mixture and stir til thickened.
Add cheese to mixture and stir over low heat until melted and smooth.
To serve, put a large spoonful of mashed potatoes on plate, top with a chicken thigh and drizzle each thigh with some of the beer/cheese sauce. Garnish with chopped chives.