Beat first three ingredients at medium speed with electric mixer until fluffy. Flavor to taste with salt and pepper.
Line a loaf pan with plastic wrap, leaving enough over edges to fold over bottom of torte. Layer one-third of the cheese mixture, one-third of the pesto, and one-third of the tomatoes. Repeat, ending with cheese mixture.
Cover with plastic wrap and refrigerate. When ready to serve, invert onto serving platter and sprinkle with walnuts.