Preheat the oven to 400°F. Line a baking sheet with foil or use cooking spray to lightly coat and then set aside.
Bring a pot of salted water to a boil over medium-high heat and then add in the potatoes. Boil the potatoes for about 15-20 minutes or until the potatoes are fork-tender when pierced.
Drain the potatoes and spread them onto the prepared baking sheet. Use a fork/potato masher or the bottom of a glass to gently press down onto the potatoes to smash them open a bit.
In a small bowl, combine the butter, olive oil, and minced garlic together and stir to combine. Evenly drizzle the mixture (or use a pastry brush) over the potatoes. Toss together to fully coat. Note: feel free to season the potatoes with salt/pepper, to taste.
Roast the potatoes until golden brown and crispy, about 20-25 minutes or until desired crispiness level is achieved.
Add the whipped feta into a bowl or spread it onto a serving platter and top/pair alongside the crispy garlic potatoes. Garnish with fresh dill and a few cracks of freshly ground black pepper, if desired. Enjoy!