Wow your guests with this classic French beef-and-puff pastry entrée.

MAKES: 8 to 10 servings
HANDS-ON TIME: 1 hour
REFRIGERATION TIME: 1 hour
TOTAL TIME: 3 hours & 30 minutes

INGREDIENTS

• 1.125 to 1.35 kg tenderloin premium oven roast  
• 1/2 tsp salt 
• 1 tbsp vegetable oil 

Mushroom Duxelles

• 3 shallots 
• 650 g cremini mushrooms 
• 3 tbsp unsalted butter 
• 1/4 tsp salt 
• 1/3 cup red wine 
• 3 cloves garlic, finely grated or pressed
• 4 1/2 tsp prepared horseradish 
• 1 tbsp Dijon mustard 
• 2 tsp finely chopped fresh thyme or 1 tsp dried thyme
• 2 tsp sodium-reduced soy sauce 
• 1/2 tsp pepper 

Assembly

• 12 slices prosciutto 
• 3 sheets (1 1/2 pkg) frozen butter puff pastry, thawed  
• 1 large egg, lightly beaten 
• 1/4 tsp flaked sea salt 

METHOD

Pat roast dry with paper towels and sprinkle with salt; rub to coat. In large nonstick skillet, heat oil over medium-high heat; brown roast, turning occasionally, on all sides, 4 to 7 minutes. Refrigerate for 30 minutes. 

Mushroom Duxelles: Meanwhile, In food processor, pulse shallots until minced; set aside. Working in batches, pulse mushrooms until finely chopped. In same skillet, melt butter over medium-high heat; sauté shallots, mushrooms and salt, stirring frequently, until no liquid remains, 10 to 15 minutes. Add wine, garlic, horseradish, mustard, thyme, soy sauce and pepper; cook, stirring frequently, until mixture begins to brown and no liquid remains, 5 to 10 minutes. Remove from heat; let cool completely. 

Assembly: Remove twine from roast, if necessary. On work surface, place two 2-foot long pieces of plastic wrap, overlapping 1 inch on long sides. Arrange prosciutto vertically in 2 rows along centre of plastic wrap, overlapping slightly to create rectangle large enough to enclose roast. Evenly spread Mushroom Duxelles over prosciutto, leaving 1-inch border. Place roast in centre; roll up prosciutto tightly, tucking in ends to seal completely. Roll up plastic wrap tightly; refrigerate for 30 minutes. 

Preheat oven to 425°F. Stack 2 large rimmed baking sheets to create double layer; line with parchment paper.

Place 1 pastry sheet on prepared baking pans. Cut second pastry sheet into 2 pieces, one 3 inches wide and one 7 inches wide. Place 1 long end of 3-inch piece against bottom end of pastry sheet on pan to create 13- x 10-inch rectangle; using fingers, press together to adhere. Carefully remove plastic wrap from roast. Place roast lengthwise in centre of 13- x 10-inch pastry; brush pastry surrounding roast with some of the egg. 

Cover top half of roast with remaining whole pastry sheet; cover rest of roast with 7-inch piece, overlapping slightly. Using hands, press pastry against sides of roast to seal edges. Trim all but 1 inch of the excess pastry around base; crimp. (Use excess pastry to make decorative cutouts, if desired.) Brush all over with remaining egg; using tip of knife, score top. Sprinkle with salt. 

Bake until instant-read thermometer inserted in centre of roast reads 120°F, 40 to 45 minutes. Let rest for 30 minutes before slicing.

Test Kitchen Tip: Assemble roast a day ahead; refrigerate, covered in plastic wrap, overnight. Before baking, brush pastry with remaining egg, then bake as directed, increasing cooking time by 5 minutes.

NUTRITIONAL FACTS

Per each of 10 servings: about 521 cal, 37 g pro, 30 g total fat (14 g sat. fat), 24 g carb (3 g dietary fibre, 3 g sugar), 118 mg chol, 813 mg sodium, 839 mg potassium. % RDI: 3% calcium, 39% iron, 10% vit A, 2% vit C, 8% folate.