Slice the chicken breasts in half horizontally to create thinner, more even pieces, then season generously with salt and pepper on both sides. Mince the garlic cloves, thinly slice the shallot, chop the spinach, tear the fresh basil, grate the Parmesan, and drain the sun-dried tomatoes, setting everything aside. Heat the olive oil in a large skillet over medium-high heat until shimmering, then sear the chicken for 1-2 minutes per side until golden but not cooked through—the chicken will finish cooking later in the sauce. Transfer the seared chicken to a plate and set aside.

In the same skillet, melt the butter over medium heat, then add the sliced shallot, minced garlic, and red pepper flakes. Sauté for about 3-4 minutes until softened and fragrant, stirring occasionally to prevent sticking. Add the drained sun-dried tomatoes and dry orzo, stirring constantly for 1-2 minutes to lightly toast the orzo and coat it with the buttery aromatics—this step adds depth and helps the orzo absorb flavors better.

Pour in the white wine and use a wooden spoon to scrape up any browned bits stuck to the bottom of the pan—these browned bits contain concentrated flavor and are essential for depth. Once the wine has reduced slightly (about 1 minute), stir in the Dijon mustard and thyme, then pour in the vegetable stock. Bring the mixture to a boil, then reduce heat to a gentle simmer.

Return the seared chicken breasts to the skillet, nestling them into the orzo mixture. Cover the skillet and simmer for 10-15 minutes, stirring occasionally, until the orzo is tender, the liquid is mostly absorbed, and the chicken is cooked through (internal temperature of 165°F). I like to stir gently every few minutes to ensure even cooking and prevent the orzo from sticking to the bottom.

Transfer the cooked chicken to a cutting board and slice it thin. Reduce the heat to low and stir the heavy cream and grated Parmesan into the orzo mixture until the cheese melts and creates a silky sauce, about 1-2 minutes. Fold in the chopped spinach and torn basil, stirring gently until the spinach wilts completely, then finish with lemon juice and taste for seasoning, adjusting salt and pepper as needed. I find that the brightness of lemon juice really brings out the Tuscan flavors in this dish, so don't skip it!

Divide the creamy orzo mixture among serving bowls or plates, then top each portion with the sliced chicken breast. Garnish with a few fresh basil leaves for color and extra Tuscan flavor.