01 - In stand mixer bowl, combine flour, sugar, yeast, and salt. Mix briefly to distribute evenly.
02 - Add eggs and lukewarm milk to dry ingredients. Mix on low speed with dough hook until shaggy dough forms, about 1-2 minutes.
03 - Increase speed to medium and knead for 5 minutes. Gradually add softened butter cubes, allowing each addition to fully incorporate before adding more. Continue kneading until dough is smooth, elastic, and pulls away from bowl sides, approximately 10 minutes.
04 - Transfer dough to lightly greased bowl, cover with plastic wrap or damp towel. Place in warm, draft-free area until doubled in size, about 1 to 1.5 hours.
05 - Line 9x5-inch loaf pan with parchment paper, leaving overhang on sides for easy removal.
06 - Punch down risen dough to release air. On lightly floured surface, roll into rectangle approximately 10x16 inches, maintaining even thickness throughout.
07 - Spread raspberry jam evenly over dough surface, leaving 1/2-inch border on all edges. Sprinkle crushed fresh raspberries over jam if desired.
08 - Starting from long side, tightly roll dough into log. Slice log lengthwise down center to expose layers. Twist two halves together, keeping cut sides facing upward to showcase swirl.
09 - Gently transfer twisted dough into prepared loaf pan, tucking ends underneath. Arrange so twist pattern is visible on top.
10 - Cover loosely with plastic wrap or towel. Let rise until puffed and noticeably increased in volume, about 45 minutes.
11 - Preheat oven to 350°F during final minutes of second rise.
12 - Whisk together egg and milk for egg wash. Brush generously over entire surface of risen loaf.
13 - Bake for 30 to 35 minutes until golden brown on top and loaf sounds hollow when tapped on bottom. If top browns too quickly, tent loosely with foil after 20 minutes.
14 - Let cool in pan for 10 minutes. Using parchment overhang, lift loaf from pan and transfer to wire rack. Cool completely before slicing to prevent filling from oozing.