Pat chicken breasts dry and season with salt and pepper. Heat olive oil and 1 tbsp butter in a skillet over medium-high heat. Sear chicken for 2-3 minutes per side until browned (do not cook through). Let cool completely on a plate. Do not wash the skillet.

Mix softened cream cheese, whole grain mustard, 1 minced garlic clove, and chopped thyme in a small bowl.

Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.

Roll out puff pastry sheets slightly and cut each in half to make 4 rectangles. Spread the cream cheese mixture onto the center of each rectangle. Place a cooled chicken breast on top.

Wrap the pastry over the chicken to completely enclose it. Place seam-side down on the baking sheet. Brush with egg wash and lightly score the tops with a knife.

Bake for 25-30 minutes until the pastry is deep golden brown and the chicken reaches an internal temperature of 165°F (74°C).

While baking, make the sauce: Return the chicken skillet to medium heat and melt 2 tbsp butter. Sauté the shallot for 2 mins, then add garlic for 30 seconds.

Pour in white wine to deglaze the pan, scraping up browned bits. Simmer until reduced by half.

Whisk in chicken broth, heavy cream, and Dijon mustard. Simmer for 5-8 minutes until thickened. Stir in fresh thyme, season with salt and pepper, and serve poured over the baked Wellingtons.