Line a plate with paper towels. Line a rimmed baking sheet with a silicone mat and set aside.
Heat a large nonstick skillet over medium-high heat. Add the bacon and cook until crisp, about 5 minutes. Remove with a slotted spoon to the prepared plate. Pour off all but a film of the grease on the bottom of the pan. (Just eyeball it instead of trying to measure, but it should be just about 1/2 teaspoon; discard the remaining grease.)
To make the salad, return the skillet to low heat. Add the onion and the diced apple. Season with salt and pepper. Add the kale; cook until the kale begins to wilt, stirring occasionally, about 2 minutes. Add the vinegar; cover, and cook until just tender, stirring occasionally, about 4 minutes. Remove from the heat, taste, and adjust for seasoning with salt and pepper.
Meanwhile, preheat the oven to broil. Place the finely chopped pecans in a shallow dish and season with salt and pepper. Roll the goat cheese log in the pecans to evenly coat. Refrigerate until firm if necessary, then cut evenly into 6 rounds and place each round of cheese on the sliced apple. Place on the prepared baking sheet. Transfer to the oven and broil until the cheese is melted and browned, 3 to 5 minutes.
To serve, divide the kale salad among the plates. Top with an apple-cheese round and garnish with the reserved bacon. Serve immediately.