Preheat the oven to 350 degrees F.
Put the oats on a baking sheet and bake, stirring occasionally, until toasty-smelling and golden brown, 10 to 15 minutes.
Bring 2 cups water to a simmer in a small saucepan. Stir in the toasted oats, cover and simmer, stirring once or twice, until the oats are tender but still slightly chewy, 25 to 30 minutes. Spread the oats on a baking sheet and refrigerate until cool, about 15 minutes.
Meanwhile, toss the raspberries, strawberries, sugar and lemon juice in a small bowl and gently mix to combine. Let sit at room temperature for at least 15 minutes to allow the berries to release their juices.
Whisk together the cream, honey and vanilla extract in a chilled bowl until soft peaks form. Fold in the whiskey, then add the oatmeal and fold it almost completely in, leaving the mixture a bit streaky. Put some of the oatmeal cream in the bottoms of 4 small Mason jars or parfait glasses. Top with spoonfuls of berries with their juices. Repeat, and then dollop a spoonful of oatmeal cream on top. Drizzle with honey and garnish with mint sprigs.