Preheat the oven to 375°F and lightly spray a muffin tin with cooking spray.
Clean and peel the potatoes and slice into 1/8-inch slices. Repeat with the beets: wash peel and slice.
*Tips: Choose potatoes and beets that are close to each other in diameter; this is not essential but will help with the presentation of the finished dish. Wearing plastic gloves while working with the beets will protect your hands from turning pink.
Add the butter, garlic, herbs and salt into a small saucepan and heat until butter is melted.
Toss the sliced potatoes in the butter mixture and ensure that they are thoroughly coated. Remove the potatoes and set into a separate bowl. Then add the sliced beets to the butter mixture and toss to coat well.
*Tips: Tossing them separately makes sure the beet color doesn't bleed into the potatoes.
Line a baking sheet with parchment paper and begin creating the herbed beet and potato stacks by placing a beet slice onto the parchment paper, then topping with a slice of potato and continue to alternate, making sure to end on the same vegetable you started with.
Bake for 40 to 50 minutes until cooked through and the edges begin to become slightly crispy and browned.
Remove from the pan and place stacks onto a platter.
Top each one with a dollop of Horseradish Dill Sauce and garnish with a sprinkling of dried dill or a sprig of fresh dill.