In a saucepan, heat milk and butter, until the butter is melted. Let cool to 120-130 F.
In the bowl of an electric mixer, combine 1 cup of the bread flour, rye flour, oats, honey, sour cream. salt, fennel seed and yeast. Mix to combine.
Add milk. Using the dough hook attachment, beat for a few minutes until you have a shaggy dough.
Add the rest of the bread flour 1/4 cup at a time until the dough comes together. You know you’ve added enough flour when the dough starts to wrap around the dough hook. (I added 3/4 cup) Knead for about 5 minutes, until smooth and elastic.
Place dough in a lightly greased bowl. Cover with plastic wrap sprayed with non stick spray and a kitchen towel. Leave to rise until doubled in size, 45 minutes – 1 1/2 hours, depending on how warm the climate is where you live.
Spray a muffin tin with non stick spray.
Turn dough onto a lightly floured board and knead for a minute or two.
Divide dough into 10 equally sized balls. Each ball should weigh about 3.3 oz.
Toss each ball back and forth from hand to hand and roll on the board using the palm of your hand to get smooth balls. Divide each ball into 3 equal sized pieces. Roll each piece into a little ball.
Place all 3 balls into one cavity of the muffin tin. Repeat for the remaining 9 balls of dough.
Cover with a clean kitchen towel and leave to rise until doubled, 30 minutes – 1 hour.
Preheat oven to 375 F.
Brush the tops with the melted butter and sprinkle the poppy seeds on top.
Bake for 30 minutes