HEAT oven to 400ºF.
ROAST beets in oven 1 hour or until softened, but still firm. (A skewer should have little resistance when used to puncture roasted beets.) Cool the beets in ice water, then remove skins. Cut beets into 32 wedges. Set aside.
PLACE cream cheese in a food processor; sprinkle with 1/4 tsp. salt. Process until creamy, gradually adding the walnut oil.
MIX the lemon zest, juice, olive oil and sugar in a small bowl. Drizzle over the beets. Season with remaining 1/4 tsp. salt.
SMEAR a little of the walnut-flavored cream cheese onto each baguette slice. Top with walnuts, raspberries, blackberries and arugula.