Prepare the potatoes. Peel and dice the Yukon Gold potatoes into approximately 1-inch pieces. Preheat the oven to 425°F.
Parboil the potatoes. Bring a large pot of water to a boil. Add the kosher salt and baking soda, then carefully add the potatoes. Boil for 10–15 minutes, or until fork-tender but not falling apart.
Prepare the seasoning. While the potatoes cook, soften the beef tallow if needed by running the container under warm water. Mix the softened tallow with the hot sauce, garlic powder, onion powder, paprika, and cayenne pepper.
Rough up the potatoes. Drain the potatoes well and transfer them to a large metal bowl. Toss with the beef tallow mixture, being slightly rough with the potatoes to create a starchy coating. This helps create those crispy, golden edges.
Arrange for roasting. Spread the potatoes in a single layer on a large baking sheet, leaving space between the pieces. Use two pans if necessary to avoid overcrowding.
Roast until crispy. Bake for 40–60 minutes, stirring every 15 minutes, until the potatoes are deeply golden and crispy on the outside.
Make the optional Boursin spread. While the potatoes roast, mix the Boursin cheeses and Greek yogurt until smooth and creamy. Spread the mixture across the bottom of a serving platter.
Assemble and serve. Spoon the hot, crispy potatoes over the Boursin spread. Garnish with freshly chopped parsley and serve immediately.