Step 1: Preheat your oven to a cozy 375°F (190°C). This ensures it's nice and hot when your cruffins are ready to bake.
Step 2: Lightly flour your work surface – a big cutting board or clean counter works great. Carefully unroll your thawed puff pastry. If it cracks a little, don't worry, just gently press it back together.
Step 3: Take that lovely 1/2 cup of melted butter and brush it evenly all over the surface of your puff pastry. Make sure you get it right to the edges!
Step 4: In a small bowl, combine your 1 cup of sugar and 2 tablespoons of cinnamon. Give it a good whisk until it's perfectly blended.
Step 5: Now, generously sprinkle that glorious cinnamon sugar mixture evenly over the buttered pastry. You want a good, thick coating for maximum flavor.
Step 6: Using a sharp knife or a pizza cutter, cut the pastry into triangles. Aim for about 8-10 triangles per sheet, depending on how big you want your cruffins to be.
Step 7: Starting from the wide base of each triangle, gently roll it up towards the tip. You'll see those beautiful cinnamon sugar layers start to form.
Step 8: Lightly grease a muffin tin (or line with paper liners if you prefer). Place each rolled-up pastry into a muffin cup. They'll puff up nicely!
Step 9: In a tiny bowl, whisk your egg with a teaspoon of water (this is your egg wash). Lightly brush the tops of your cruffins with this mixture. This gives them that irresistible golden crust.
Step 10: Pop that muffin tin into your preheated oven and bake for 20-25 minutes, or until your cruffins are beautifully golden brown and puffed up. Every oven is a little different, so keep an eye on them!
Step 11: Once they're out of the oven, let them cool in the tin for a few minutes before transferring them to a wire rack. They're best served warm, but are still delicious at room temperature.