In a small bowl whisk together 1 egg and 1 tablespoon lemon juice until well beaten; set aside.
In another shallow bowl combine the all-purpose flour, garlic powder, and paprika; mix to blend.
Place each chicken breast between two sheets of waxed paper and pound with a meat mallet or rolling pin until evenly flattened to about 1/4–1/2-inch thickness.
Pat the chicken dry with paper towels so the coating adheres well.
Dip each chicken breast into the egg-lemon mixture, then dredge in the flour mixture, shaking off excess flour.
Melt the butter in a large skillet over medium-high heat.
Add the coated chicken breasts and sear for 2 to 3 minutes per side until golden brown.
Meanwhile dissolve the chicken bouillon in 1/2 cup hot water.
Pour the bouillon mixture and the remaining 2 tablespoons lemon juice into the skillet with the chicken and bring to a boil.
Cover the skillet, reduce the heat to low, and simmer for 10 to 15 minutes until the chicken is cooked through (no longer pink inside).
Transfer the chicken to plates, spoon the pan sauce over each breast, and top with capers and lemon slices to serve.