Special equipment: pizza cutter or kitchen shears, ruler

Preheat the oven to 400 degrees F. Line 2 baking sheets with parchment paper.

Place 1 sheet thawed puff pastry on the work surface like a sheet of paper or portrait (not horizontal or landscape). If the puff pastry is very sticky, very lightly flour the work surface. Using a pizza cutter or kitchen shears, cut the puff pastry in half, widthwise. Using a ruler as a guide, make an indentation at 2-inch intervals (for the base) across the bottom of each puff pastry half. Cut each half into 8 triangles, with the base of each triangle measuring 2 inches. (They will be very long isosceles triangles.) You'll end up discarding the 2 end pieces to get the most out of your puff pastry piece. This sheet of triangles will be reserved for the chocolate croissants. Repeat the cutting for the second puff pastry sheet that will be used for the almond croissants.

For the chocolate croissants: Place 1 chocolate piece just above the 2-inch edge of 1 pastry triangle, folding the dough over the chocolate as you tightly roll up the dough, enclosing the chocolate. Repeat with the remaining puff pastry and chocolate. Place the pastry rolls on the baking sheet, seam-side down. Cover the croissants with plastic wrap and place the baking sheet in the refrigerator until the dough firms up. (You can make these croissants 1 day ahead up to this point.)

Just before baking, remove the croissants from the refrigerator, brush with the beaten egg and sprinkle lightly with sugar.

For the almond croissants: Place 1/2 to 1 teaspoon almond paste, shaped like a small log, just above the 2-inch edge of 1 pastry triangle, folding the dough over the almond paste as you tightly roll up the dough, enclosing the almond paste. Repeat with remaining puff pastry triangles and almond paste. Place the pastry rolls on a baking sheet, seam-side down. Cover the croissants with plastic wrap and place in the refrigerator until the dough firms up. (You can make these croissants 1 day ahead up to this point.)

Just before baking, remove the croissants from the refrigerator, brush with the beaten egg and sprinkle lightly with sugar and sliced almonds.

Bake until the pastries are golden brown, about 15 minutes. Serve warm or at room temperature.

Cook's Note: These croissants are so easy and so good you'll want to stuff them with practically everything. They are perfect as is-chocolate croissants and almond croissants, but if you're feeling a little adventurous combine the chocolate and almond paste (scale back just a touch on the almond paste) in one croissant for a decadent treat. But don't stop there, you can stuff these mouthwatering minis with savory fillings too. Ham and cheese croissants are crazy good!