Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Dice the russet potato into 1/2-inch cubes and place them in a mixing bowl.
Toss the potato cubes with 0.25 tbsp of olive oil, dried rosemary, sea salt, and black pepper until evenly coated.
Spread the potatoes in a single layer on the baking sheet and roast for 25-30 minutes, or until they are golden and crispy.
While the potatoes roast, mince the garlic and chop the fresh parsley.
In a large skillet over medium heat, add the remaining 0.25 tbsp of olive oil and the minced garlic, sautéing for about 30 seconds until fragrant.
Add the shrimp to the skillet and cook for 2-3 minutes per side until they are opaque and pink.
Remove the skillet from heat, drizzle the lemon juice over the shrimp, and toss with the fresh parsley.
Serve the garlic shrimp immediately over the warm roasted potatoes.