Puff Pastry Squares with Botifarra Sausage and Mushrooms

This is an extraordinary tapa that utilizes a famous sausage from Catalonia called botifarra (in Catalan) or butifarra (in Spanish). It is the most common of Catalan pork sausages and is spiced with cinnamon, fennel seeds, and black pepper. You can replace this sausage with kielbasa or chicken sausage or order the Catalan sausage from donajuna.com or another reputable source. If using frozen puff pastry, defrost according to package instructio