Place the yeast and sugar in the bowl of a stand mixer fitted with a dough hook or paddle attachment. Or, if you do not own a stand mixer, a regular large mixing bowl. Heat the milk on the stove or in the microwave until warm to touch, about 110°F (43°C). Pour warm milk on top of yeast/sugar. Whisk gently to combine, then loosely cover with a clean kitchen towel and allow to sit for 5-10 minutes. The mixture will be frothy after 5-10 minutes.

Add the butter, egg, flour, and salt. Beat on low speed for 4 minutes. Dough will be soft.

Keep the dough in the mixer and beat for an additional 5 full minutes, or knead by hand on a lightly floured surface for 5 full minutes. (If you’re new to bread-baking, my How to Knead Dough video tutorial can help here.) If the dough becomes too sticky during the kneading process, sprinkle 1 teaspoon of flour at a time on the dough or on the work surface/in the bowl to make a soft, slightly tacky dough. Do not add more flour than you need because you do not want a dry dough. After kneading, the dough should still feel a little soft. Poke it with your finger—if it slowly bounces back, your dough is ready to rise. You can also do a “windowpane test” to see if your dough has been kneaded long enough: tear off a small (roughly golfball-size) piece of dough and gently stretch it out until it’s thin enough for light to pass through it. Hold it up to a window or light. Does light pass through the stretched dough without the dough tearing first? If so, your dough has been kneaded long enough and is ready to rise. If not, keep kneading until it passes the windowpane test.

Place the dough in a greased bowl (I use nonstick spray to grease) and cover with plastic wrap or aluminum foil. Place in a slightly warm environment to rise until doubled in size, about 90 minutes. For this warm spot, I suggest using the oven. Preheat to 200°F (93°C), then turn the oven off after preheating. Place the covered bowl inside and shut the oven door. This is your warm environment.

Grease a 9-inch springform pan. Turn the risen dough out onto a lightly floured work surface, punch it down to release the air.

Using a rolling pin, roll into a 12×16 inch rectangle. Spread jam evenly on top. If desired, dot randomly with raspberries. Tightly roll up the dough to form a 16-inch long log. Place the log on its seam. Using a sharp knife, cut the log in half lengthwise. I find a serrated knife works best. Criss-cross one half on top of the other half—forming an X. Twist the two together then coil into a circle. Carefully transfer to prepared springform pan. (I carefully pick it up using two flat spatulas!) Cover the twist with plastic wrap or aluminum foil, then allow to rise once again in a slightly warm environment until puffy, about 45 minutes.

Adjust the oven rack to the lower third position then preheat oven to 350°F (177°C).

Bake until golden brown, about 40-45 minutes. If you find the top is browning too quickly, tent with aluminum foil. Remove from the oven and allow to cool for 5 minutes. Meanwhile, make the vanilla icing by whisking the icing ingredients together until smooth.

Carefully remove the rim of the springform pan. Drizzle with vanilla icing. Slice and serve. Cover and store leftovers in the refrigerator for up to 1 week.