In a medium bowl, stir together cream cheese and heavy cream until smooth.: You will notice the cream cheese soften and the mixture loosen as the heavy cream blends in, creating a pale, glossy base. Stirring should produce a silky texture that ribbons slightly when the spoon lifts, which signals the right consistency. If you feel resistance or see lumps, let the cream cheese sit for a few minutes to warm, then continue; forcing cold cheese will leave grainy bits. A common mistake is overwhipping, which can make the mixture too airy and change the mouthfeel, so stir just until smooth.
Stir in remaining ingredients and chill at least an hour before serving to let flavors meld.: As you fold in the chopped red onion , capers , dill , horseradish , and smoked salmon , you will see flecks of color and texture distributed through the creamy base. The aroma will shift, with salty and herby notes becoming more pronounced, and you might detect the smokiness right away. Chilling allows those flavors to integrate and helps the spread firm up for easier spreading, while also damping any raw edge from the onion. A frequent misstep is serving immediately; that can make the flavors feel disjointed, so give it the hour if possible. If the mixture seems too loose after chilling, a short rest at cooler temperature helps it firm without adding more cheese.
Serve with toasted bagels, crackers, or veggie sticks.: When plated, the spread should hold its shape but still be soft enough to spread easily, leaving a glossy trail on crackers or bagel halves. Toasting bagels brings out warm, crisp edges that contrast wonderfully with the cold, creamy spread, and you will notice how the smoke becomes more pronounced against the toast. If you hear a gentle crunch from the toasted bread it indicates the right level of toast, whereas a soggy base means it sat too long before serving. One trap is overloading each bite with toppings which can mask the spread, so keep additions light to let the core flavors sing.
