1. Remove and discard skin and bones from trout, if necessary. Flake trout into small pieces.
2. Pulse cream cheese and next 8 ingredients in a food processor 7 to 8 times or until combined, stopping to scrape down sides as needed. Stir in flaked trout pieces. Transfer to a serving dish. Serve immediately, or cover and chill up to 2 days. If chilled, let stand 30 minutes at room temperature before serving. Serve with apple slices, celery sticks, and flatbread crackers. Garnish, if desired.
Smoked Salmon-and-Horseradish Spread: Substitute 2 (4-oz.) packages smoked salmon, finely chopped, for trout. Omit Step 1. Proceed with recipe as directed.
Party Tip: Keep sliced apples or pears from browning by tossing them with lemon-lime soda. It works just like lemon juice but without the sour taste. The citric acid in the soda will keep the fruit looking fresh.