Cook the strawberries, brown sugar, and lemon juice over medium-high heat, stirring occasionally. Use a potato masher or the back of a wooden spoon to mash the berries as they cook. When they start to thicken, combine the cornstarch and water and stir it into the berries. Continue cooking until the jam is super thick and paste-like, about 2-4 minutes longer. Stir in the strawberry extract if using, transfer to a bowl, and set aside to cool.

In a small saucepan, whisk together the water and flour. Cook over medium heat, whisking constantly, for 4-5 minutes until the mixture is a paste-like slurry. Scrape it into a bowl and set it aside until ready to use.

In a stand mixer bowl, mix the flour, sugar, yeast, and salt. Add the cream, milk, egg, vanilla, and tangzhong to the bowl. Knead on low speed with the dough hook for 2 minutes until it forms a rough dough ball.

With the mixer running on low, add the softened butter one tablespoon at a time, letting it fully incorporate before adding more. Then, continue kneading for another 8-10 minutes or until the dough looks smooth and elastic.

Remove the dough from the bowl and pull the sides into the bottom to create a smooth round ball. Place it seam-side down back into the mixing bowl. Cover with plastic wrap and set aside to rest for 30 minutes.

While the dough rests, make the filling. In a large bowl, combine the butter, brown sugar, and cinnamon until smooth. Set aside.

Place the rested dough on a lightly floured surface. Roll it out into a 15×21 rectangle. Dollop the cinnamon sugar filling across the surface of the dough, then use an offset spatula to gently spread it across, leaving a ½-inch border clean at the top. Then spread all but 1-2 tablespoons of the strawberry jam on top in the same way. The reserved jam will be used in the frosting!

Use a pizza cutter to cut twelve 1 ¾-inch strips. Roll each strip away from you, then carefully transfer them to a parchment-lined 9×13 baking pan.

Cover the pan with plastic wrap and set it aside to rise for 1-2 hours, or until the rolls have doubled in size. Meanwhile, preheat the oven to 325°F/162°C.

Bake for 30-40 minutes or until the internal temperature of the center rolls reaches 185°F. Let them cool on a wire rack while you make the frosting.

In a medium bowl, combine the butter, cream cheese, and powdered sugar until smooth. Then whisk in the milk, reserved strawberry jam, and strawberry extract. Spread over the sweet rolls and enjoy!