Begin by finely chopping one small yellow onion and peeling and mincing four cloves of garlic. Coarsely chop the fronds from one small bunch of fresh dill until you have amassed two tablespoons. Segment eight ounces of cream cheese into eight equal pieces. Thoroughly dry four boneless, skinless chicken breasts using paper towels and season uniformly with one teaspoon of kosher salt and half a teaspoon of black pepper.

In a large skillet, heat two tablespoons of olive oil over medium-high heat until it begins to shimmer. Place the chicken in the skillet and sear, turning once midway through, until golden brown on both surfaces, approximately 10 minutes in total. Remove the chicken to a plate; note that it will not be fully cooked at this point.

Add the remaining two tablespoons of olive oil to the skillet and heat until shimmering. Introduce the chopped onion and sauté, stirring occasionally, until tender, about two minutes. Add the minced garlic and continue to cook, stirring continuously, until it is fragrant and golden-brown, approximately one minute additional. Carefully pour in half a cup of dry white wine and let it simmer, scraping up any browned bits from the bottom of the skillet, until the wine has nearly evaporated, about one minute.

Pour in one and a half cups of low-sodium chicken broth. Add the segmented cream cheese, two teaspoons of Dijon mustard, the remaining half teaspoon of kosher salt, and the remaining quarter teaspoon of black pepper. Bring the mixture to a simmer, whisking frequently, until the cream cheese has completely melted and is well-incorporated. Adjust the seasoning with additional kosher salt and black pepper if necessary.

Return the chicken along with any accumulated juices to the skillet. Bring the mixture back to a simmer, then cover and reduce the heat to medium. Allow it to simmer until the chicken is thoroughly cooked, about three to five minutes more. Remove from heat and garnish with the chopped dill and one-quarter teaspoon of red pepper flakes before serving.