Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
Place the baby potatoes in a large pot and cover with water. Bring to a boil and cook until the potatoes are fork-tender, about 15-20 minutes. Drain the potatoes and let them cool slightly.
Arrange the boiled potatoes on the prepared baking sheet. Using a potato masher or the bottom of a glass, gently smash each potato until it's flattened but still in one piece.
Drizzle the smashed potatoes with olive oil and season with salt and pepper. Roast in the preheated oven until crispy and golden brown, about 20-25 minutes.
While the potatoes are roasting, prepare the dressing. In a large bowl, mix together the Boursin cheese, mayonnaise, Dijon mustard, and apple cider vinegar until smooth. Stir in the chopped red onion.
Once the potatoes are done, let them cool for a few minutes. Then add the crispy potatoes to the bowl with the dressing and gently toss until all the potatoes are coated.
Stir in the chopped parsley and dill. Taste and adjust the seasoning if necessary.
Serve the crispy smashed potato salad warm or at room temperature.