Place potatoes in a large pot and cover with salted water. Bring water to a boil over high heat, and then reduce to a simmer until potatoes are tender, about 15-20 minutes. With 5 minutes remaining, add the frozen peas. Drain.
In a large skillet, melt butter and garlic together over medium heat. Stir in flour and whisk until a paste forms with the butter. Add in milk, a little at a time, whisking it constantly until it thickens - about 5 minutes.
Season with turmeric and salt and pepper, stirring to fully combine. Taste, adding more salt if needed.
Add potatoes and peas to cream sauce, and stir to fully coat them. Continue to cook for 5 minutes until everything is heated thoroughly.
Remove from stove and allow to sit for 5-10 minutes before serving. This allows the cream sauce to thicken as it cools down.
Serve in bowls and enjoy this comforting potatoes and peas meal!