Add the chicken to a ziptop bag or bowl with a lid.
To a blender add the shallots, garlic, wine, rosemary, dijon salt and pepper. Blend until smooth Pour the marinade over the chicken and make sure all pieces are well covered. Seal and refrigerate for 2 hours
Make the sauce:
Melt the butter in a skillet over medium heat.
Add the shallots, garlic and rosemary and cook until softened about 5 minutes.
Mix the flour into the shallots and butter. Cook for 1 minute, stirring. Stir in the wine, salt and pepper, scraping all the bits off the bottom of the pan and simmer for 2 minutes until slightly reduced. Add the mustard and chicken stock, mix well. Simmer until thickened.
Transfer the sauce to a blender and blend until smooth. Set aside.
Cook the chicken:
Preheat outdoor grill on high.
Thread the chicken pieces onto skewers and grill 5 minutes per side.