Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a skillet, melt butter over medium heat. Add onions and bell peppers. Cook until soft and caramelized, about 8–10 minutes.
Toss in the cooked steak. Season with salt and pepper. Heat through and set aside.
For the dough, melt shredded mozzarella and cream cheese together until smooth. Mix in almond flour, baking powder, and eggs until a dough forms.
Divide the dough into four equal parts. Roll out each into a rectangle between two sheets of parchment.
Layer each with steak mixture and a slice of cheese. Roll gently into logs.
Place on baking sheet. Bake for 15–18 minutes until golden brown. Let cool slightly before serving.