Potato Leek Bourekas - Breaking Matzo

Ingredients

• 1 potato (about 10-12 oz), peeled & roughly chopped
• 2 tbsp butter (or olive oil) + extra if needed to smooth out potato mixture
• 1 leek, finely chopped (white part only), about 1/2 cup
• 1 tsp paprika
• 1 tsp cumin
• pinch of cinnamon
• 1/2 tsp salt
• 1 clove garlic, minced
• 2 tsp fresh rosemary, very finely chopped (optional)
• 1 pound puff pastry sheets
• flour for rolling out puff pastry (or roll pastry between parchment or plastic wrap sheets)
• 1 egg, beaten with 1 tsp water
• 2 tbsp sesame seeds (mix of black and white makes nice presentation)