01 - Combine flour, sugar, yeast, and salt in the bowl of a stand mixer.
02 - Add eggs and lukewarm milk to the dry ingredients. Mix on low speed with a dough hook until a shaggy dough forms.
03 - Increase mixer speed to medium and knead for 5 minutes. Gradually add softened butter, a few cubes at a time, until fully incorporated and the dough becomes smooth and elastic, approximately 10 minutes.
04 - Transfer the dough to a lightly greased bowl, cover, and let rise in a warm, draft-free area until doubled in size, about 1 to 1.5 hours.
05 - Line a 9x5-inch loaf pan with parchment paper.
06 - Punch down the risen dough and roll out on a lightly floured surface into a rectangle approximately 10x16 inches.
07 - Spread raspberry jam evenly over the dough, leaving a 1/2-inch border around the edges. Sprinkle with crushed fresh raspberries if desired.
08 - Starting from a long side, tightly roll the dough into a log. Slice the log lengthwise down the center to expose the layers, then twist the two halves together with cut sides facing up.
09 - Gently transfer the twisted dough into the prepared loaf pan. Cover and let rise until puffed, approximately 45 minutes.
10 - Preheat the oven to 350°F.
11 - Whisk together the egg and milk for the egg wash. Brush the mixture evenly over the risen loaf.
12 - Bake for 30 to 35 minutes, or until the loaf is golden brown and sounds hollow when tapped on the bottom.
13 - Allow the loaf to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.