In a medium saucepan, combine cubed peaches, granulated sugar, and lemon juice over medium heat. Cook until thickened, about 10-15 minutes. Stir in cornstarch mixture, cook for 2 more minutes, then cool completely.

In a small saucepan, whisk together equal parts of flour and water over medium heat, stirring for 2-3 minutes until thickened. Let it cool.

In a stand mixer bowl, combine all-purpose flour, sugar, instant yeast, and sea salt. Gradually add milk, egg, vanilla extract, and cooled tangzhong. Mix until shaggy, then knead in softened butter for 8-10 minutes.

In a mixing bowl, combine melted butter, flour, brown sugar, and cinnamon until crumbly. Chill in the refrigerator.

Roll risen dough onto a floured surface, spread brown sugar filling, peach jam, and peach slices. Roll tightly and slice, placing in a greased baking dish. Let rise for 30-45 minutes.

Preheat oven to 325°F (162°C). Sprinkle chilled crumb topping over rolls and bake for 25-30 minutes until golden brown.

Blend cream cheese and softened butter until smooth, then whisk in powdered sugar and heavy cream. Drizzle over warm rolls.