Preheat the oven to 450°F (230°C). Line a large baking sheet with parchment paper or lightly grease it.
Place the baby Yukon gold potatoes in a large pot and cover with cold water. Add a pinch of salt to the water.
Bring the water to a boil over high heat, then reduce to a simmer. Cook the potatoes until they are fork-tender, about 15-20 minutes.
Drain the potatoes and let them cool slightly until safe to handle.
Place the potatoes on the prepared baking sheet, spacing them evenly.
Using the bottom of a sturdy glass or a potato masher, gently press down on each potato to smash it to about 1/2 inch thickness. Be careful not to break them apart completely.
Drizzle the smashed potatoes evenly with olive oil.
Sprinkle the garlic powder, 1 teaspoon sea salt, and black pepper evenly over the potatoes.
Bake in the preheated oven for 25-30 minutes, or until the potatoes are golden brown and crispy on the edges.
Remove the potatoes from the oven and immediately drizzle the malt vinegar over them while still hot.
Sprinkle additional sea salt to taste and toss gently to coat the potatoes evenly with the vinegar and seasoning.
Garnish with chopped fresh parsley before serving.