Preheat oven to 350F. Arrange bread slices in a single layer on a rimmed baking sheet. Brush both side with oil, and bake until lightly toasted and crisp, 8 to 10 minutes. Transfer to a wire rack to cool completely.
To serve, dollop ricotta onto each crostini, season with coarse salt, and top as desired.
Top each toast with 3 to 4 cherry- or grape-tomato halves and a sprig of basil. Drizzle with extra-virgin olive oil and sprinkle with flaky sea salt (such as Maldon)