01 - Season the chicken breasts generously with salt, black pepper, and garlic powder on both sides, pressing the seasoning into the meat to ensure adhesion.
02 - Heat olive oil and butter in a large skillet over medium-high heat until butter foams. Add chicken breasts and sear for 4-5 minutes per side until golden brown and nearly cooked through. Remove chicken and set aside on a warm plate, reserving any accumulated juices.
03 - Reduce heat to medium. Add chopped shallot and minced garlic to the same skillet, sautéing for 2-3 minutes until softened and fragrant, being careful not to brown the garlic.
04 - Pour in chicken broth, scraping up any browned bits from the bottom of the skillet with a wooden spoon. Allow the mixture to simmer for 2 minutes to reduce slightly.
05 - Stir in heavy cream, Dijon mustard, and chopped fresh dill. Bring the mixture to a gentle simmer, stirring constantly to incorporate the mustard and prevent curdling.
06 - Return chicken breasts and any reserved juices to the skillet. Simmer on low heat for 6-8 minutes until chicken is completely cooked through and the sauce has thickened enough to coat the back of a spoon.
07 - Stir in lemon juice and taste the sauce. Adjust seasoning with additional salt or pepper if needed. The sauce should be rich, creamy, and well-balanced.
08 - Plate chicken breasts with generous sauce coverage. Garnish with additional fresh dill sprigs and serve immediately while hot.