In the bowl of a stand mixer, add the 2 1/2 teaspoons yeast and 1 1/2 cup lukewarm milk. Stir to dissolve, then mix in 7 tablespoons softened butter and one egg.
In another bowl, combine the 4 1/2 cup flour, 1 tablespoon brown sugar, 1 1/2 teaspoon salt, 2 teaspoons cardamom, 1 cup dried cranberries, 1 cup raisins, and 1 cup chopped walnuts.
Add the dry ingredients to the milk mixture and give it a good stir with a spatula or a wooden spoon to combine.
Attach the dough hook and turn the mixer on to the lowest speed. Mix until flour is incorporated, scraping down the sides of the bowl as necessary.
Increase speed to medium and beat for 2 minutes or until a ball of dough is formed. Alternatively, knead the dough by hand on a floured surface.
Mix the dough on low speed until smooth, elastic, and slightly tacky, adding more flour by the tablespoonfuls if needed, about 4 minutes.
Transfer the dough to a floured surface and knead for about 2 minutes, then return to the bowl, cover with cling film sprayed with cooking spray and leave to rise for 1-2 hours or until its volume has doubled.
Place the risen dough on a floured surface and knead gently again, then form it into 24 smooth, round buns. Place them on prepared baking sheets lined with parchment paper or Silpat. Cover with kitchen towels and leave to rise for 30 minutes longer.
Preheat the oven to 400 degrees Fahrenheit.
Brush the risen buns with a beaten egg and sprinkle with raw sugar if desired. Bake for 20-25 minutes until golden and slightly firm to the touch. Cool completely on a wire rack.
Keep the bowl with the dough near (not on) a heat source to speed up the rising process.
Measure out all the ingredients before you get started as this recipe comes together super fast.
The milk is what activates the yeast. You don't want it too hot, or it'll kill the yeast (it's recommended somewhere between 100-110F). You can warm it in the microwave in a glass measuring cup and then use this thermometer to check the temperature. Or stick your finger in it like I do to check if it's warm enough (baby bottle warm).
Making the rolls the same size ensures an even baking time. You can eyeball it or pat the dough into a rectangle about 8 x 12 inches. Cut into 4 strips and then cut those strips into 6 squares for a total of 24 rolls. You can use a kitchen scale to weigh them too.
When rolling the dough into balls, pull the "seams" down to the bottom and twist it, so it's nice and smooth on top.
Check the rolls at 15 minutes. If they are starting to darken beyond what you prefer, put a piece of foil over the top. Always check a center roll for doneness and then tent with foil if they need a few more minutes. Just keep a close watch on them.
You can brush the hot buns with butter - this is what gives their top that irresistible golden sheen.
You can toast the nuts before adding them to the dough. To toast the nuts, preheat your oven at 400 Fahrenheit. Place them on a baking sheet and toast for 10 minutes.
Instead of walnuts, you can use hazelnuts or sunflower seeds.
The buns are only slightly sweet. If you prefer them sweeter, add another tablespoon of sugar.