1. Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
2. Season the chicken breasts with salt and pepper. Heat a skillet over medium-high heat with a drizzle of olive oil. Sear each chicken breast for about 2 minutes per side until golden but not fully cooked. Remove from heat and let cool slightly.
3. In the same skillet, melt butter over medium heat. Add shallots and garlic, cooking until soft and fragrant, about 2 minutes.
4. Add the finely chopped mushrooms and thyme to the pan. Cook, stirring occasionally, until the mushrooms release their moisture and the mixture becomes thick and pasty, about 8-10 minutes. Season with salt and pepper. Remove from heat and let cool.
5. Spread a thin layer of Dijon mustard over each chicken breast. Then, lay two slices of prosciutto on a piece of plastic wrap, slightly overlapping, and spread half of the mushroom mixture over the prosciutto.
6. Place one chicken breast on top of the mushroom mixture and use the plastic wrap to tightly roll the prosciutto and mushrooms around the chicken. Repeat with the remaining chicken breasts.
7. Roll out the puff pastry sheet on a lightly floured surface. Cut it into four equal squares.
8. Unwrap each prosciutto-wrapped chicken breast and place it in the center of a puff pastry square. Fold the pastry over the chicken, sealing the edges with a bit of beaten egg. Trim any excess pastry if needed, and press gently to seal.
9. Place each wrapped chicken breast seam-side down on the prepared baking sheet. Brush the tops with beaten egg for a beautiful golden finish.
10. Bake in the preheated oven for 25-30 minutes or until the pastry is golden brown and an instant-read thermometer inserted into the chicken reads 165°F (74°C).
11. Allow the Chicken Wellington to rest for 5 minutes before serving. This helps the juices redistribute, keeping the chicken tender and juicy.

One of my favorite tips, inspired by Mama Lou, is to take your time with the mushroom duxelles. The slow cooking and reduction are what give this dish its soul, so don’t rush it! And if you’re making this with Ouma, it’s the perfect recipe to share while swapping stories.