Preheat oven to 350 degrees F. Put the cherry tomatoes in a small roasting dish, drizzle with 1 tablespoon of olive oil and roast for 30 minutes, turning half way through roasting. Remove from oven, cover and set aside.
In a large skillet set over medium-high heat, add 1 tablespoon of the olive oil and garlic. Fry for just a minute and add the onions. Reduce heat to medium-low and cook until soft and browned, around 10 minutes. Remove onions from pan and set aside.
Next, coat the chicken in the flour. You can do this by putting the flour and the chicken in a zip-lock bag, sealing it up and shaking it until all the chicken pieces are coated. Using the reserved pan, add the remaining tablespoon of olive oil and the chicken. Make sure you shake off the excess flour before adding it to the pan. Just cook the chicken for a few minutes until it is browned on the outside but not cooked through. Just about 3 minutes or so. Remove chicken from pan and set aside.
With the same skillet set over medium heat, now add the butter, paprika, mustard and 1 tablespoon of the flour. Using a whisk, stir until it forms a paste. This is happen quite quickly. Start adding your stock gradually, whisking as you go until you have a smooth texture.
Toss the chicken back into the sauce and simmer for about 10 minutes or until chicken is tender and cooked.
In a separate skillet set over high heat, add the remaining olive oil and garlic slices. Sautee for about a minute and toss in the spinach until wilted.
Serve the Chicken with the spinach and topped with cherry tomatoes.