Add flour to a shallow bowl; place a large skillet over med-high heat; add 1 tablespoon olive oil and the butter to the skillet.
Dredge chicken in flour; season with salt and pepper.
Add chicken to skillet; cook 7-8 minutes or until browned.
Add in wine; scrape up browned bits as wine comes to a bubble; cook the liquid down, 30 seconds to a minute.
Combine the half-and-half and mustard; pour over the chicken.
Add grapes to the skillet and shake or toss to coat the chicken and grapes in the sauce.
Lower heat to low and simmer 3-5 minutes.
Meanwhile, make the couscous—bring the chicken broth and a drizzle of olive oil to a boil; add in the couscous.
Remove pan from heat and cover; let sit for 5 minutes, then fluff with a fork.
Serve mounds of couscous with chicken and grapes alongside or on top.