You can make your dough in a large mixing bowl, as directed below. Or you can make your dough in the bowl of a stand mixer with a dough hook attachment. 

• In a small saucepan over medium heat, warm the milk until it reaches 110 degrees F.
• Pour the warm milk into a large mixing bowl, add the instant yeast, and whisk gently. Allow the mixture to sit for 3 minutes, or until the yeast is bubbly and smells very yeasty. Be sure that your milk isn’t too hot when you add it to the bowl. If the milk is too warm, it can kill the yeast!
• Add the salt, butter, sugar, and eggs to the yeast mixture and mix. (I love to use my Danish dough whisk for this, but you can also use a wooden spoon or your hands.) Add the 4 cups of flour, and mix until a shaggy dough forms.
• Turn the dough out on a lightly floured surface and knead until the dough is smooth and soft, about 5 minutes.
• Return your ball of dough to the bowl, and cover it with plastic wrap or a clean kitchen towel. Place the bowl in a warm spot to rise. Allow the dough to rise until it is doubled in size, about 30 minutes. Though the rise times will vary slightly depending on the temperature of your house.  
• After your dough has risen, punch it down and turn it out onto a lightly floured work surface, and using a rolling pin, roll the dough into a large rectangle, about 1/4 inch thick.
• Spoon half of your melted butter over your rolled dough, and spread it out so it covers all of the dough, leaving roughly 1/4 inch gap around the edge. 
• Then spoon your blackberry jam in dollops over the dough, and spread it out with a rubber spatula or the back of a spoon, doing your best to keep it evenly spread over all the dough.
• Sprinkle the chopped blackberries over the jam, and finally drizzle your remaining melted butter over the top of the berries. 
• Then, starting on one of the long sides of your dough, fold over roughly a 1/2 inch and gently press it down. Gently roll the dough up(like a cinnamon roll), doing your best to keep it as tight as possible, until you have a finished log/roll.
• Using a sharp knife, cut the log into 12-16 rolls, depending on how large and thick you want them. I usually make 16. Grease a 9×13 baking dish, and arrange your rolls in the pan. Cover and set in a warm place for 30 minutes. This will be your second rise
• Preheat the oven to 375 degrees F.
• Once the rolls after doubled in size, place the pan in the oven and bake for 30-35 minutes or until golden brown. 
• While your sweet rolls are baking, prep your cream cheese icing.
• Place your cream cheese and soft butter into a large bowl, and beat with an electric mixer on medium speed until smooth and creamy. Add the vanilla extract and beat to combine. Reduce your beaters to low speed, and add the powdered sugar 1/2 cup at a time, mixing well between each addition. 
• Scrape down the sides of the bowl, add the milk, and beat until smooth. Add more milk if needed until you have reached a drizzable consistency.
• Once the rolls are cooked, remove them from the oven and allow them to cool for 15-20 minutes before drizzling the cream cheese icing over the top. 
• Serve warm and enjoy!