Heat oven to 400°F.
Grease 15 x 10-inch pan; line with waxed paper; grease paper; flour.
Melt margarine in saucepan. Stir in flour, salt, pepper; cook, stirring, 1 minute, until thickened. Whisk in milk; cook, whisking, until thickened, 4 minutes; remove from heat. Beat yolks in bowl. Whisk in a little milk mixture. Whisk into pan.
Beat whites until stiff. Fold quarter of whites into yolk mixture; fold in remaining whites. Spread in prepared pan.
Bake in 400°F oven until set, about 18 minutes. Cover with clean towel and larger baking sheet. Hold pan and sheet securely together; turn over, unmolding roulade onto baking sheet. Remove pan and waxed paper.
Put cheese and ham on roulade; spread with mustard. Using towel as guide, roll up from short end. Slice.