01 - In a stand mixer bowl, combine flour, sugar, yeast, and salt. Mix briefly to distribute evenly.
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 speed to medium and knead for 5 minutes. Gradually add softened butter, a few cubes at a time, until fully incorporated. Continue kneading until dough is smooth and elastic, approximately 10 minutes.
04 - Transfer dough to a lightly greased bowl, cover with plastic wrap or a damp towel, and let rise in a warm place until doubled in size, about 1 to 1.5 hours.
05 - Line a 9x5-inch loaf pan with parchment paper, leaving overhang on the long sides for easy removal.
06 - Punch down the risen dough and transfer to a lightly floured surface. Roll out 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 lightly crushed fresh raspberries if desired.
08 - Starting from a long side, tightly roll the dough into a log. Use a sharp knife to slice the log lengthwise down the center, exposing the layers. Twist the two halves together, keeping the cut sides facing up.
09 - Gently transfer the twisted dough into the prepared loaf pan, tucking the ends underneath. Cover loosely and let rise until puffed, about 45 minutes.
10 - Preheat oven to 350°F (175°C) during the final 15 minutes of the second rise.
11 - Whisk together egg and milk for the egg wash. Brush generously over the entire surface of the risen loaf.
12 - Bake for 30 to 35 minutes, or until the loaf is deeply golden brown and sounds hollow when tapped on the bottom. If the top browns too quickly, tent loosely with foil.
13 - Let the loaf cool in the pan for 10 minutes, then use the parchment overhang to transfer to a wire rack. Cool completely before slicing for clean cuts.