In a large bowl combine water, starter, salt and flour. Mix until most of the flour has been combined. Cover and let sit for 30 minutes.
While the dough is resting shred the cold butter. Alternatively, you can cut the butter into small cubes (1/4").
Add in shredded butter and fold into dough until well combined.
Perform 2 sets of stretch and folds 30-60 minutes apart if desired.
Cover and let ferment for 8-10 hours. I like to mix this up in the morning and let it sit during the day so I can keep an eye on the dough.
In a small bowl combine brown sugar, all purpose flour, and melted butter. Mix to combine. Set aside the crumble mixture
After the dough has doubled in size pour onto the counter and gently stretch into a rectangle. Spread raspberry jam and sprinkle crumble mixture over the top. Fold dough into thirds, and top with another later of jam and crunble. Reserving 1/4 cup of crumble mixture for later. Fold dough into thirds again and flip the dough over and shape using a push and pull motion. Do this gently, you do not want the surface to tear, but want the folds no longer visible. The dough will be more prone to ripping with the inclusions.
Alternatively, you can place the dough into a standard loaf pan if shaping is intimidating or your dough rips.
Sprinkle the loaf with flour and place into a small bowl (or banneton basket). Cover and let proof for 30-90 minutes on the counter. While the dough is on its final proof preheat a dutch oven inside your oven at 450. You want the Dutch oven nice and hot!
After your dough has proofed, flip onto a piece of parchment paper and score the loaf.
Gently place your parchment lined loaf into your dutch oven. Bake covered at 450 for 20 minutes.
Uncover the loaf and top with remaining crumble mixture. Continue baking at 425 for 20 minutes. Your crust should be nice and golden brown when it is done. If you aren’t sure if your loaf is completely cooked, use a thermometer to see if the internal temperature reaches 190 F.