Step 1

Place a rack in middle of oven; preheat to 300°. Spread out brioche on a rimmed baking sheet. Bake, tossing halfway through and reducing oven temperature if browning too fast, until brioche is very dry and lightly toasted, 25–35 minutes. Let cool.

Step 2

Meanwhile, bring condensed milk and half-and-half to a bare simmer in a medium saucepan over medium heat. Remove from heat and whisk in granulated sugar, salt, and vanilla until sugar is dissolved. Add tea bags and let sit 25 minutes.

Step 3

Remove tea bags from pan, wringing them out over pan; discard tea bags. Whisk egg yolks and egg into tea mixture until incorporated.

Step 4

Increase oven temperature to 350°. Butter a 13x9" baking dish. Arrange brioche in an even layer in baking dish and scatter raisins on top. Pour custard mixture over; toss brioche to coat, then press down lightly to partially submerge. Let sit 20 minutes to give brioche time to soak up custard.

Step 5

Bake bread pudding until golden brown and custard is puffed and just set (it should barely jiggle when gently shaken), 35–40 minutes. Let cool 20 minutes before serving.

Step 6

Meanwhile, heat ice cream in a small saucepan over low heat, stirring occasionally, until melted and just warmed through (do not simmer), 5–8 minutes. Transfer crème anglaise to a small pitcher or bowl.

Step 7

Dust bread pudding with powdered sugar, then cut into squares and divide among plates. Drizzle crème anglaise over and arrange lychees around if desired. Serve remaining crème anglaise alongside.