The crepes can be made through step 3 up to a day ahead; wrap them well in plastic, then refrigerate until ready.
Crepes: Puree raspberries in a food processor until smooth. Pass through a fine sieve into a bowl, pressing on solids to remove as much liquid as possible (you should have 1 cup).
Whisk together flour, granulated sugar, and salt in a bowl. Whisk together eggs, 2 cups milk, and vanilla in another bowl. Pour milk mixture into flour mixture; whisk to combine. Whisk in melted butter and raspberry puree. Pass mixture through sieve, then refrigerate until well chilled, at least 2 hours. Batter should have consistency of thick heavy cream; if needed, whisk in more milk to thin.
Heat a 10-inch nonstick skillet over medium-high heat. Brush very lightly with butter. Pour in 1/3 cup batter while turning and tilting skillet quickly to coat bottom evenly. Cook until edges of crepe are golden and top is dry, about 1 minute, 30 seconds. Run a spatula around edge to loosen, then flip over. Cook until bottom is firm and golden in spots, about 20 seconds. Transfer to a plate; repeat with remaining batter, brushing pan with butter, if needed, and lowering heat to medium if crepes are browning too quickly. Stack crepes with a sheet of parchment between each.
Cream: Whisk together heavy cream, sour cream, and confectioners' sugar in a bowl just until firm peaks form.
Assembly: Place 1 crepe on a serving plate or cake stand. Spread 3 tablespoons cream mixture on top. Arrange a scant 3/4 cup nectarine slices to cover most of crepe. Scatter some raspberries on top. Spread with 3 more tablespoons cream. Place a second crepe on top, pressing to flatten and spread cream to edges. Continue layering cream, fruit, more cream, and crÃªpes, using 8 crepes total and all the fruit. Spoon remaining cream on top. Sprinkle with almonds and refrigerate until set, at least 3 hours and up to 8 hours. Cut into slices; serve.