Position two chopsticks around a potato to create a physical block for your knife - this helps you avoid cutting through the potato, creating that "accordion effect."
Using a sharp knife, place deep cuts in the potato every 1/4" stopping when your blade hits the chopsticks.
Repeat for all potatoes.
Place the potatoes on a lined cookie sheet.
Melt half of the butter and olive oil in a saucepan with the smashed garlic cloves and thyme. Pour over the potatoes, ensuring you get in as many of those cuts as possible.
Bake the potatoes for 50-60 minutes, until golden and crispy.
Melt the remaining butter and olive oil with the garlic and thyme.
Brush the melted butter-oil mixture on top of the crispy potatoes.
Season with salt and pepper and garnish if desired.