The dressing is made from rendered fat from diced pancetta, sautéed shallots, a splash of balsamic vinegar whisked with brown sugar, and dijon mustard served warm over tender baby spinach leaves.
Add the pancetta to a large sauté pan and heat over medium-low heat until the fat has rendered and the pancetta is crispy, about 5 minutes. Remove the pancetta to a bowl, reserving as much of the rendered fat as possible in the pan.
Return the pan to medium heat, add the olive oil and heat through. Add the shallot and sauté until tender, about 4 minutes.
Lower heat to medium-low, then add the balsamic, brown sugar and dijon, whisking to combine. Season to taste with salt and pepper.
Add the spinach to a large bowl and toss with the warm dressing. Add the apple and cornichons and toss once more. Serve immediately.
Notes
Swaps and substitutions
I love the sweetness of Honeycrisp apples, but tart green apples can also be used.